diff --git a/fixtures/references.php b/fixtures/references.php
new file mode 100644
index 0000000..6cb9190
--- /dev/null
+++ b/fixtures/references.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace TestNamespace;
+
+$obj = new TestClass();
+$obj->testMethod();
+echo $obj->testProperty;
+TestClass::staticTestMethod();
+echo TestClass::$staticTestProperty;
+echo TestClass::TEST_CLASS_CONST;
+test_function();
+
+$var = 123;
+echo $var;
+
+function whatever(TestClass $param): TestClass {
+    echo $param;
+}
+
+$fn = function() use ($var) {
+    echo $var;
+};
+
+echo TEST_CONST;
diff --git a/fixtures/symbols.php b/fixtures/symbols.php
index 03281c5..26379e4 100644
--- a/fixtures/symbols.php
+++ b/fixtures/symbols.php
@@ -2,10 +2,19 @@
 
 namespace TestNamespace;
 
-class TestClass
+const TEST_CONST = 123;
+
+class TestClass implements TestInterface
 {
+    const TEST_CLASS_CONST = 123;
+    public static $staticTestProperty;
     public $testProperty;
 
+    public static function staticTestMethod()
+    {
+
+    }
+
     public function testMethod($testParameter)
     {
         $testVariable = 123;
@@ -21,3 +30,24 @@ interface TestInterface
 {
 
 }
+
+function test_function()
+{
+
+}
+
+new class {
+    const TEST_CLASS_CONST = 123;
+    public static $staticTestProperty;
+    public $testProperty;
+
+    public static function staticTestMethod()
+    {
+
+    }
+
+    public function testMethod($testParameter)
+    {
+        $testVariable = 123;
+    }
+};
diff --git a/fixtures/use.php b/fixtures/use.php
new file mode 100644
index 0000000..28e3aec
--- /dev/null
+++ b/fixtures/use.php
@@ -0,0 +1,6 @@
+<?php
+
+namespace SecondTestNamespace;
+
+use TestNamespace\TestClass;
+use TestNamespace\{TestTrait, TestInterface};
diff --git a/src/LanguageServer.php b/src/LanguageServer.php
index 83c2167..cee9faa 100644
--- a/src/LanguageServer.php
+++ b/src/LanguageServer.php
@@ -103,6 +103,9 @@ class LanguageServer extends \AdvancedJsonRpc\Dispatcher
         $serverCapabilities->workspaceSymbolProvider = true;
         // Support "Format Code"
         $serverCapabilities->documentFormattingProvider = true;
+        // Support "Go to definition"
+        $serverCapabilities->definitionProvider = true;
+
         return new InitializeResult($serverCapabilities);
     }
 
diff --git a/src/ColumnCalculator.php b/src/NodeVisitor/ColumnCalculator.php
similarity index 96%
rename from src/ColumnCalculator.php
rename to src/NodeVisitor/ColumnCalculator.php
index 9050264..6f6b3bf 100644
--- a/src/ColumnCalculator.php
+++ b/src/NodeVisitor/ColumnCalculator.php
@@ -1,7 +1,7 @@
 <?php
 declare(strict_types = 1);
 
-namespace LanguageServer;
+namespace LanguageServer\NodeVisitor;
 
 use PhpParser\{NodeVisitorAbstract, Node};
 
diff --git a/src/NodeVisitor/DefinitionCollector.php b/src/NodeVisitor/DefinitionCollector.php
new file mode 100644
index 0000000..9032155
--- /dev/null
+++ b/src/NodeVisitor/DefinitionCollector.php
@@ -0,0 +1,28 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\NodeVisitor;
+
+use PhpParser\{NodeVisitorAbstract, Node};
+
+/**
+ * Collects definitions of classes, interfaces, traits, methods, properties and constants
+ * Depends on ReferencesAdder and NameResolver
+ */
+class DefinitionCollector extends NodeVisitorAbstract
+{
+    /**
+     * Map from fully qualified name (FQN) to Node
+     *
+     * @var Node[]
+     */
+    public $definitions = [];
+
+    public function enterNode(Node $node)
+    {
+        $fqn = $node->getAttribute('ownerDocument')->getDefinedFqn($node);
+        if ($fqn !== null) {
+            $this->definitions[$fqn] = $node;
+        }
+    }
+}
diff --git a/src/NodeVisitor/NodeAtPositionFinder.php b/src/NodeVisitor/NodeAtPositionFinder.php
new file mode 100644
index 0000000..b6b9cc1
--- /dev/null
+++ b/src/NodeVisitor/NodeAtPositionFinder.php
@@ -0,0 +1,47 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\NodeVisitor;
+
+use PhpParser\{NodeVisitorAbstract, Node};
+use LanguageServer\Protocol\{Position, Range};
+
+/**
+ * Finds the Node at a specified position
+ * Depends on ColumnCalculator
+ */
+class NodeAtPositionFinder extends NodeVisitorAbstract
+{
+    /**
+     * The node at the position, if found
+     *
+     * @var Node
+     */
+    public $node;
+
+    /**
+     * @var Position
+     */
+    private $position;
+
+    /**
+     * @param Position $position The position where the node is located
+     */
+    public function __construct(Position $position)
+    {
+        $this->position = $position;
+    }
+
+    public function leaveNode(Node $node)
+    {
+        $range = Range::fromNode($node);
+        // Workaround for https://github.com/nikic/PHP-Parser/issues/311
+        $parent = $node->getAttribute('parentNode');
+        if (isset($parent) && $parent instanceof Node\Stmt\GroupUse && $parent->prefix === $node) {
+            return;
+        }
+        if (!isset($this->node) && $range->includes($this->position)) {
+            $this->node = $node;
+        }
+    }
+}
diff --git a/src/NodeVisitor/ReferencesAdder.php b/src/NodeVisitor/ReferencesAdder.php
new file mode 100644
index 0000000..f3f912f
--- /dev/null
+++ b/src/NodeVisitor/ReferencesAdder.php
@@ -0,0 +1,55 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\NodeVisitor;
+
+use PhpParser\{NodeVisitorAbstract, Node};
+use LanguageServer\Protocol\{SymbolInformation, SymbolKind, Range, Position, Location};
+
+/**
+ * Decorates all nodes with parent and sibling references (similar to DOM nodes)
+ */
+class ReferencesAdder extends NodeVisitorAbstract
+{
+    /**
+     * @var Node[]
+     */
+    private $stack = [];
+
+    /**
+     * @var Node
+     */
+    private $previous;
+
+    /**
+     * @var mixed
+     */
+    private $document;
+
+    /**
+     * @param mixed $document The value for the ownerDocument attribute
+     */
+    public function __construct($document = null)
+    {
+        $this->document = $document;
+    }
+
+    public function enterNode(Node $node)
+    {
+        $node->setAttribute('ownerDocument', $this->document);
+        if (!empty($this->stack)) {
+            $node->setAttribute('parentNode', end($this->stack));
+        }
+        if (isset($this->previous) && $this->previous->getAttribute('parentNode') === $node->getAttribute('parentNode')) {
+            $node->setAttribute('previousSibling', $this->previous);
+            $this->previous->setAttribute('nextSibling', $node);
+        }
+        $this->stack[] = $node;
+    }
+
+    public function leaveNode(Node $node)
+    {
+        $this->previous = $node;
+        array_pop($this->stack);
+    }
+}
diff --git a/src/PhpDocument.php b/src/PhpDocument.php
index febff0e..9979d6a 100644
--- a/src/PhpDocument.php
+++ b/src/PhpDocument.php
@@ -3,8 +3,8 @@ declare(strict_types = 1);
 
 namespace LanguageServer;
 
-use \LanguageServer\Protocol\{Diagnostic, DiagnosticSeverity, Range, Position, SymbolKind, TextEdit};
-
+use LanguageServer\Protocol\{Diagnostic, DiagnosticSeverity, Range, Position, SymbolInformation, SymbolKind, TextEdit, Location};
+use LanguageServer\NodeVisitor\{NodeAtPositionFinder, ReferencesAdder, DefinitionCollector, ColumnCalculator};
 use PhpParser\{Error, Comment, Node, ParserFactory, NodeTraverser, Lexer, Parser};
 use PhpParser\PrettyPrinter\Standard as PrettyPrinter;
 use PhpParser\NodeVisitor\NameResolver;
@@ -23,7 +23,9 @@ class PhpDocument
      *
      * @var Project
      */
-    private $project;
+    public $project;
+    // for whatever reason I get "cannot access private property" error if $project is not public
+    // https://github.com/felixfbecker/php-language-server/pull/49#issuecomment-252427359
 
     /**
      * The PHPParser instance
@@ -47,9 +49,25 @@ class PhpDocument
     private $content;
 
     /**
-     * @var SymbolInformation[]
+     * The AST of the document
+     *
+     * @var Node[]
      */
-    private $symbols = [];
+    private $stmts = [];
+
+    /**
+     * Map from fully qualified name (FQN) to Node
+     *
+     * @var Node[]
+     */
+    private $definitions = [];
+
+    /**
+     * Map from fully qualified name (FQN) to array of nodes that reference the symbol
+     *
+     * @var Node[][]
+     */
+    private $references;
 
     /**
      * @param string         $uri     The URI of the document
@@ -68,22 +86,54 @@ class PhpDocument
     /**
      * Returns all symbols in this document.
      *
-     * @return SymbolInformation[]
+     * @return SymbolInformation[]|null
      */
     public function getSymbols()
     {
-        return $this->symbols;
+        if (!isset($this->definitions)) {
+            return null;
+        }
+        $nodeSymbolKindMap = [
+            Node\Stmt\Class_::class           => SymbolKind::CLASS_,
+            Node\Stmt\Trait_::class           => SymbolKind::CLASS_,
+            Node\Stmt\Interface_::class       => SymbolKind::INTERFACE,
+            Node\Stmt\Namespace_::class       => SymbolKind::NAMESPACE,
+            Node\Stmt\Function_::class        => SymbolKind::FUNCTION,
+            Node\Stmt\ClassMethod::class      => SymbolKind::METHOD,
+            Node\Stmt\PropertyProperty::class => SymbolKind::PROPERTY,
+            Node\Const_::class                => SymbolKind::CONSTANT
+        ];
+        $symbols = [];
+        foreach ($this->definitions as $fqn => $node) {
+            $class = get_class($node);
+            if (!isset($nodeSymbolKindMap[$class])) {
+                continue;
+            }
+            $symbol = new SymbolInformation();
+            $symbol->kind = $nodeSymbolKindMap[$class];
+            $symbol->name = (string)$node->name;
+            $symbol->location = Location::fromNode($node);
+            $parts = preg_split('/(::|\\\\)/', $fqn);
+            array_pop($parts);
+            $symbol->containerName = implode('\\', $parts);
+            $symbols[] = $symbol;
+        }
+        return $symbols;
     }
 
     /**
      * Returns symbols in this document filtered by query string.
      *
      * @param string $query The search query
-     * @return SymbolInformation[]
+     * @return SymbolInformation[]|null
      */
     public function findSymbols(string $query)
     {
-        return array_filter($this->symbols, function($symbol) use(&$query) {
+        $symbols = $this->getSymbols();
+        if ($symbols === null) {
+            return null;
+        }
+        return array_filter($symbols, function($symbol) use ($query) {
             return stripos($symbol->name, $query) !== false;
         });
     }
@@ -104,7 +154,7 @@ class PhpDocument
      * Re-parses a source file, updates symbols, reports parsing errors
      * that may have occured as diagnostics and returns parsed nodes.
      *
-     * @return \PhpParser\Node[]
+     * @return void
      */
     public function parse()
     {
@@ -138,16 +188,30 @@ class PhpDocument
         // $stmts can be null in case of a fatal parsing error
         if ($stmts) {
             $traverser = new NodeTraverser;
-            $finder = new SymbolFinder($this->uri);
+
+            // Resolve aliased names to FQNs
             $traverser->addVisitor(new NameResolver);
+
+            // Add parentNode, previousSibling, nextSibling attributes
+            $traverser->addVisitor(new ReferencesAdder($this));
+
+            // Add column attributes to nodes
             $traverser->addVisitor(new ColumnCalculator($this->content));
-            $traverser->addVisitor($finder);
+
+            // Collect all definitions
+            $definitionCollector = new DefinitionCollector;
+            $traverser->addVisitor($definitionCollector);
+
             $traverser->traverse($stmts);
 
-            $this->symbols = $finder->symbols;
-        }
+            $this->definitions = $definitionCollector->definitions;
+            // Register this document on the project for all the symbols defined in it
+            foreach ($definitionCollector->definitions as $fqn => $node) {
+                $this->project->addDefinitionDocument($fqn, $this);
+            }
 
-        return $stmts;
+            $this->stmts = $stmts;
+        }
     }
 
     /**
@@ -157,14 +221,13 @@ class PhpDocument
      */
     public function getFormattedText()
     {
-        $stmts = $this->parse();
-        if (empty($stmts)) {
+        if (empty($this->stmts)) {
             return [];
         }
         $prettyPrinter = new PrettyPrinter();
         $edit = new TextEdit();
         $edit->range = new Range(new Position(0, 0), new Position(PHP_INT_MAX, PHP_INT_MAX));
-        $edit->newText = $prettyPrinter->prettyPrintFile($stmts);
+        $edit->newText = $prettyPrinter->prettyPrintFile($this->stmts);
         return [$edit];
     }
 
@@ -177,4 +240,294 @@ class PhpDocument
     {
         return $this->content;
     }
+
+    /**
+     * Returns the URI of the document
+     *
+     * @return string
+     */
+    public function getUri(): string
+    {
+        return $this->uri;
+    }
+
+    /**
+     * Returns the node at a specified position
+     *
+     * @param Position $position
+     * @return Node|null
+     */
+    public function getNodeAtPosition(Position $position)
+    {
+        if ($this->stmts === null) {
+            return null;
+        }
+        $traverser = new NodeTraverser;
+        $finder = new NodeAtPositionFinder($position);
+        $traverser->addVisitor($finder);
+        $traverser->traverse($this->stmts);
+        return $finder->node;
+    }
+
+    /**
+     * Returns the definition node for a fully qualified name
+     *
+     * @param string $fqn
+     * @return Node|null
+     */
+    public function getDefinitionByFqn(string $fqn)
+    {
+        return $this->definitions[$fqn] ?? null;
+    }
+
+    /**
+     * Returns true if the given FQN is defined in this document
+     *
+     * @param string $fqn The fully qualified name of the symbol
+     * @return bool
+     */
+    public function isDefined(string $fqn): bool
+    {
+        return isset($this->definitions[$fqn]);
+    }
+
+    /**
+     * Returns the fully qualified name (FQN) that is defined by a node
+     * Examples of FQNs:
+     *  - testFunction()
+     *  - TestNamespace\TestClass
+     *  - TestNamespace\TestClass::TEST_CONSTANT
+     *  - TestNamespace\TestClass::staticTestProperty
+     *  - TestNamespace\TestClass::testProperty
+     *  - TestNamespace\TestClass::staticTestMethod()
+     *  - TestNamespace\TestClass::testMethod()
+     *
+     * @param Node $node
+     * @return string|null
+     */
+    public function getDefinedFqn(Node $node)
+    {
+        if ($node instanceof Node\Name) {
+            $nameNode = $node;
+            $node = $node->getAttribute('parentNode');
+        }
+        // Only the class node should count as the definition, not the name node
+        // Anonymous classes don't count as a definition
+        if ($node instanceof Node\Stmt\ClassLike && !isset($nameNode) && isset($node->name)) {
+            // Class, interface or trait declaration
+            return (string)$node->namespacedName;
+        } else if ($node instanceof Node\Stmt\Function_) {
+            // Function: use functionName() as the name
+            return (string)$node->namespacedName . '()';
+        } else if ($node instanceof Node\Stmt\ClassMethod) {
+            // Class method: use ClassName::methodName() as name
+            $class = $node->getAttribute('parentNode');
+            if (!isset($class->name)) {
+                // Ignore anonymous classes
+                return null;
+            }
+            return (string)$class->namespacedName . '::' . (string)$node->name . '()';
+        } else if ($node instanceof Node\Stmt\PropertyProperty) {
+            // Property: use ClassName::propertyName as name
+            $class = $node->getAttribute('parentNode')->getAttribute('parentNode');
+            if (!isset($class->name)) {
+                // Ignore anonymous classes
+                return null;
+            }
+            return (string)$class->namespacedName . '::' . (string)$node->name;
+        } else if ($node instanceof Node\Const_) {
+            $parent = $node->getAttribute('parentNode');
+            if ($parent instanceof Node\Stmt\Const_) {
+                // Basic constant: use CONSTANT_NAME as name
+                return (string)$node->namespacedName;
+            }
+            if ($parent instanceof Node\Stmt\ClassConst) {
+                // Class constant: use ClassName::CONSTANT_NAME as name
+                $class = $parent->getAttribute('parentNode');
+                if (!isset($class->name) || $class->name instanceof Node\Expr) {
+                    return null;
+                }
+                return (string)$class->namespacedName . '::' . $node->name;
+            }
+        }
+    }
+
+    /**
+     * Returns the FQN that is referenced by a node
+     *
+     * @param Node $node
+     * @return string|null
+     */
+    public function getReferencedFqn(Node $node)
+    {
+        if ($node instanceof Node\Name) {
+            $nameNode = $node;
+            $node = $node->getAttribute('parentNode');
+        }
+
+        if (
+            ($node instanceof Node\Stmt\ClassLike
+            || $node instanceof Node\Param
+            || $node instanceof Node\Stmt\Function_)
+            && isset($nameNode)
+        ) {
+            // For extends, implements and type hints use the name directly
+            $name = (string)$nameNode;
+        // Only the name node should be considered a reference, not the UseUse node itself
+        } else if ($node instanceof Node\Stmt\UseUse && isset($nameNode)) {
+            $name = (string)$node->name;
+            $parent = $node->getAttribute('parentNode');
+            if ($parent instanceof Node\Stmt\GroupUse) {
+                $name = $parent->prefix . '\\' . $name;
+            }
+        // Only the name node should be considered a reference, not the New_ node itself
+        } else if ($node instanceof Node\Expr\New_ && isset($nameNode)) {
+            if (!($node->class instanceof Node\Name)) {
+                // Cannot get definition of dynamic calls
+                return null;
+            }
+            $name = (string)$node->class;
+        } else if ($node instanceof Node\Expr\MethodCall || $node instanceof Node\Expr\PropertyFetch) {
+            if ($node->name instanceof Node\Expr || !($node->var instanceof Node\Expr\Variable)) {
+                // Cannot get definition of dynamic calls
+                return null;
+            }
+            // Need to resolve variable to a class
+            $varDef = $this->getVariableDefinition($node->var);
+            if (!isset($varDef)) {
+                return null;
+            }
+            if ($varDef instanceof Node\Param) {
+                if (!isset($varDef->type)) {
+                    // Cannot resolve to class without a type hint
+                    // TODO: parse docblock
+                    return null;
+                }
+                $name = (string)$varDef->type;
+            } else if ($varDef instanceof Node\Expr\Assign) {
+                if ($varDef->expr instanceof Node\Expr\New_) {
+                    if (!($varDef->expr->class instanceof Node\Name)) {
+                        // Cannot get definition of dynamic calls
+                        return null;
+                    }
+                    $name = (string)$varDef->expr->class;
+                } else {
+                    return null;
+                }
+            } else {
+                return null;
+            }
+            $name .= '::' . (string)$node->name;
+        } else if ($node instanceof Node\Expr\FuncCall) {
+            if ($node->name instanceof Node\Expr) {
+                return null;
+            }
+            $name = (string)$node->name;
+        } else if ($node instanceof Node\Expr\ConstFetch) {
+            $name = (string)$node->name;
+        } else if (
+            $node instanceof Node\Expr\ClassConstFetch
+            || $node instanceof Node\Expr\StaticPropertyFetch
+            || $node instanceof Node\Expr\StaticCall
+        ) {
+            if ($node->class instanceof Node\Expr || $node->name instanceof Node\Expr) {
+                // Cannot get definition of dynamic names
+                return null;
+            }
+            $name = (string)$node->class . '::' . $node->name;
+        }
+        if (
+            $node instanceof Node\Expr\MethodCall
+            || $node instanceof Node\Expr\FuncCall
+            || $node instanceof Node\Expr\StaticCall
+        ) {
+            $name .= '()';
+        }
+        if (!isset($name)) {
+            return null;
+        }
+        // If the node is a function or constant, it could be namespaced, but PHP falls back to global
+        // The NameResolver therefor does not resolve these to namespaced names
+        // http://php.net/manual/en/language.namespaces.fallback.php
+        if ($node instanceof Node\Expr\FuncCall || $node instanceof Node\Expr\ConstFetch) {
+            // Find and try with namespace
+            $n = $node;
+            while (isset($n)) {
+                $n = $n->getAttribute('parentNode');
+                if ($n instanceof Node\Stmt\Namespace_) {
+                    $namespacedName = (string)$n->name . '\\' . $name;
+                    // If the namespaced version is defined, return that
+                    // Otherwise fall back to global
+                    if ($this->project->isDefined($namespacedName)) {
+                        return $namespacedName;
+                    }
+                }
+            }
+        }
+        return $name;
+    }
+
+    /**
+     * Returns the definition node for any node
+     * The definition node MAY be in another document, check the ownerDocument attribute
+     *
+     * @param Node $node
+     * @return Node|null
+     */
+    public function getDefinitionByNode(Node $node)
+    {
+        // Variables always stay in the boundary of the file and need to be searched inside their function scope
+        // by traversing the AST
+        if ($node instanceof Node\Expr\Variable) {
+            return $this->getVariableDefinition($node);
+        }
+        $fqn = $this->getReferencedFqn($node);
+        if (!isset($fqn)) {
+            return null;
+        }
+        $document = $this->project->getDefinitionDocument($fqn);
+        if (!isset($document)) {
+            return null;
+        }
+        return $document->getDefinitionByFqn($fqn);
+    }
+
+    /**
+     * Returns the assignment or parameter node where a variable was defined
+     *
+     * @param Node\Expr\Variable $n The variable access
+     * @return Node\Expr\Assign|Node\Param|Node\Expr\ClosureUse|null
+     */
+    public function getVariableDefinition(Node\Expr\Variable $var)
+    {
+        $n = $var;
+        // Traverse the AST up
+        while (isset($n) && $n = $n->getAttribute('parentNode')) {
+            // If a function is met, check the parameters and use statements
+            if ($n instanceof Node\FunctionLike) {
+                foreach ($n->getParams() as $param) {
+                    if ($param->name === $var->name) {
+                        return $param;
+                    }
+                }
+                // If it is a closure, also check use statements
+                if ($n instanceof Node\Expr\Closure) {
+                    foreach ($n->uses as $use) {
+                        if ($use->var === $var->name) {
+                            return $use;
+                        }
+                    }
+                }
+                break;
+            }
+            // Check each previous sibling node for a variable assignment to that variable
+            while ($n->getAttribute('previousSibling') && $n = $n->getAttribute('previousSibling')) {
+                if ($n instanceof Node\Expr\Assign && $n->var->name === $var->name) {
+                    return $n;
+                }
+            }
+        }
+        // Return null if nothing was found
+        return null;
+    }
 }
diff --git a/src/Project.php b/src/Project.php
index adf37f6..b889c8f 100644
--- a/src/Project.php
+++ b/src/Project.php
@@ -15,7 +15,15 @@ class Project
      *
      * @var PhpDocument[]
      */
-    private $documents;
+    private $documents = [];
+
+    /**
+     * An associative array [string => PhpDocument]
+     * that maps fully qualified symbol names to loaded PhpDocuments
+     *
+     * @var PhpDocument[]
+     */
+    private $definitions = [];
 
     /**
      * Instance of the PHP parser
@@ -54,6 +62,39 @@ class Project
         return $this->documents[$uri];
     }
 
+    /**
+     * Adds a document as the container for a specific symbol
+     *
+     * @param string $fqn The fully qualified name of the symbol
+     * @return void
+     */
+    public function addDefinitionDocument(string $fqn, PhpDocument $document)
+    {
+        $this->definitions[$fqn] = $document;
+    }
+
+    /**
+     * Returns the document where a symbol is defined
+     *
+     * @param string $fqn The fully qualified name of the symbol
+     * @return PhpDocument|null
+     */
+    public function getDefinitionDocument(string $fqn)
+    {
+        return $this->definitions[$fqn] ?? null;
+    }
+
+    /**
+     * Returns true if the given FQN is defined in the project
+     *
+     * @param string $fqn The fully qualified name of the symbol
+     * @return bool
+     */
+    public function isDefined(string $fqn): bool
+    {
+        return isset($this->definitions[$fqn]);
+    }
+
     /**
      * Finds symbols in all documents, filtered by query parameter.
      *
@@ -64,7 +105,10 @@ class Project
     {
         $queryResult = [];
         foreach ($this->documents as $uri => $document) {
-            $queryResult = array_merge($queryResult, $document->findSymbols($query));
+            $documentQueryResult = $document->findSymbols($query);
+            if ($documentQueryResult !== null) {
+                $queryResult = array_merge($queryResult, $documentQueryResult);
+            }
         }
         return $queryResult;
     }
diff --git a/src/Protocol/Location.php b/src/Protocol/Location.php
index d6bdc14..a1d9861 100644
--- a/src/Protocol/Location.php
+++ b/src/Protocol/Location.php
@@ -2,6 +2,8 @@
 
 namespace LanguageServer\Protocol;
 
+use PhpParser\Node;
+
 /**
  * Represents a location inside a resource, such as a line inside a text file.
  */
@@ -17,6 +19,17 @@ class Location
      */
     public $range;
 
+    /**
+     * Returns the location of the node
+     *
+     * @param Node $node
+     * @return self
+     */
+    public static function fromNode(Node $node)
+    {
+        return new self($node->getAttribute('ownerDocument')->getUri(), Range::fromNode($node));
+    }
+
     public function __construct(string $uri = null, Range $range = null)
     {
         $this->uri = $uri;
diff --git a/src/Protocol/Position.php b/src/Protocol/Position.php
index 7831268..01cff0b 100644
--- a/src/Protocol/Position.php
+++ b/src/Protocol/Position.php
@@ -26,4 +26,27 @@ class Position
         $this->line = $line;
         $this->character = $character;
     }
+
+    /**
+     * Compares this position to another position
+     * Returns
+     *  - 0 if the positions match
+     *  - a negative number if $this is before $position
+     *  - a positive number otherwise
+     *
+     * @param Position $position
+     * @return int
+     */
+    public function compare(Position $position): int
+    {
+        if ($this->line === $position->line && $this->character === $position->character) {
+            return 0;
+        }
+
+        if ($this->line !== $position->line) {
+            return $this->line - $position->line;
+        }
+
+        return $this->character - $position->character;
+    }
 }
diff --git a/src/Protocol/Range.php b/src/Protocol/Range.php
index c4a59ff..17f31da 100644
--- a/src/Protocol/Range.php
+++ b/src/Protocol/Range.php
@@ -2,6 +2,8 @@
 
 namespace LanguageServer\Protocol;
 
+use PhpParser\Node;
+
 /**
  * A range in a text document expressed as (zero-based) start and end positions.
  */
@@ -21,9 +23,34 @@ class Range
      */
     public $end;
 
+    /**
+     * Returns the range the node spans
+     *
+     * @param Node $node
+     * @return self
+     */
+    public static function fromNode(Node $node)
+    {
+        return new self(
+            new Position($node->getAttribute('startLine') - 1, $node->getAttribute('startColumn') - 1),
+            new Position($node->getAttribute('endLine') - 1, $node->getAttribute('endColumn'))
+        );
+    }
+
     public function __construct(Position $start = null, Position $end = null)
     {
         $this->start = $start;
         $this->end = $end;
     }
+
+    /**
+     * Checks if a position is within the range
+     *
+     * @param Position $position
+     * @return bool
+     */
+    public function includes(Position $position): bool
+    {
+        return $this->start->compare($position) <= 0 && $this->end->compare($position) >= 0;
+    }
 }
diff --git a/src/Protocol/SymbolInformation.php b/src/Protocol/SymbolInformation.php
index 12e9ccc..e02fd9b 100644
--- a/src/Protocol/SymbolInformation.php
+++ b/src/Protocol/SymbolInformation.php
@@ -2,6 +2,8 @@
 
 namespace LanguageServer\Protocol;
 
+use PhpParser\Node;
+
 /**
  * Represents information about programming constructs like variables, classes,
  * interfaces etc.
diff --git a/src/Server/TextDocument.php b/src/Server/TextDocument.php
index a6541c1..39a9699 100644
--- a/src/Server/TextDocument.php
+++ b/src/Server/TextDocument.php
@@ -3,7 +3,7 @@ declare(strict_types = 1);
 
 namespace LanguageServer\Server;
 
-use LanguageServer\{LanguageClient, ColumnCalculator, SymbolFinder, Project};
+use LanguageServer\{LanguageClient, ColumnCalculator, Project};
 use LanguageServer\Protocol\{
     TextDocumentItem,
     TextDocumentIdentifier,
@@ -13,7 +13,8 @@ use LanguageServer\Protocol\{
     Range,
     Position,
     FormattingOptions,
-    TextEdit
+    TextEdit,
+    Location
 };
 
 /**
@@ -88,4 +89,26 @@ class TextDocument
     {
         return $this->project->getDocument($textDocument->uri)->getFormattedText();
     }
+
+    /**
+     * The goto definition request is sent from the client to the server to resolve the definition location of a symbol
+     * at a given text document position.
+     *
+     * @param TextDocumentIdentifier $textDocument The text document
+     * @param Position $position The position inside the text document
+     * @return Location|Location[]|null
+     */
+    public function definition(TextDocumentIdentifier $textDocument, Position $position)
+    {
+        $document = $this->project->getDocument($textDocument->uri);
+        $node = $document->getNodeAtPosition($position);
+        if ($node === null) {
+            return null;
+        }
+        $def = $document->getDefinitionByNode($node);
+        if ($def === null) {
+            return null;
+        }
+        return Location::fromNode($def);
+    }
 }
diff --git a/src/Server/Workspace.php b/src/Server/Workspace.php
index cbd0da4..c6d963a 100644
--- a/src/Server/Workspace.php
+++ b/src/Server/Workspace.php
@@ -6,7 +6,7 @@ namespace LanguageServer\Server;
 use PhpParser\{Error, Comment, Node, ParserFactory, NodeTraverser, Lexer};
 use PhpParser\PrettyPrinter\Standard as PrettyPrinter;
 use PhpParser\NodeVisitor\NameResolver;
-use LanguageServer\{LanguageClient, ColumnCalculator, SymbolFinder, Project};
+use LanguageServer\{LanguageClient, ColumnCalculator, Project};
 use LanguageServer\Protocol\{
     TextDocumentItem,
     TextDocumentIdentifier,
diff --git a/src/SymbolFinder.php b/src/SymbolFinder.php
deleted file mode 100644
index f49677c..0000000
--- a/src/SymbolFinder.php
+++ /dev/null
@@ -1,121 +0,0 @@
-<?php
-declare(strict_types = 1);
-
-namespace LanguageServer;
-
-use PhpParser\{NodeVisitorAbstract, Node};
-
-use LanguageServer\Protocol\{SymbolInformation, SymbolKind, Range, Position, Location};
-
-class SymbolFinder extends NodeVisitorAbstract
-{
-    const NODE_SYMBOL_KIND_MAP = [
-        Node\Stmt\Class_::class           => SymbolKind::CLASS_,
-        Node\Stmt\Trait_::class           => SymbolKind::CLASS_,
-        Node\Stmt\Interface_::class       => SymbolKind::INTERFACE,
-        Node\Stmt\Namespace_::class       => SymbolKind::NAMESPACE,
-        Node\Stmt\Function_::class        => SymbolKind::FUNCTION,
-        Node\Stmt\ClassMethod::class      => SymbolKind::METHOD,
-        Node\Stmt\PropertyProperty::class => SymbolKind::PROPERTY,
-        Node\Const_::class                => SymbolKind::CONSTANT,
-        Node\Expr\Variable::class         => SymbolKind::VARIABLE
-    ];
-
-    /**
-     * @var LanguageServer\Protocol\SymbolInformation[]
-     */
-    public $symbols = [];
-
-    /**
-     * @var string
-     */
-    private $uri;
-
-    /**
-     * @var string
-     */
-    private $containerName;
-
-    /**
-     * @var array
-     */
-    private $nameStack = [];
-
-    /**
-     * @var array
-     */
-    private $nodeStack = [];
-
-    /**
-     * @var int
-     */
-    private $functionCount = 0;
-
-    public function __construct(string $uri)
-    {
-        $this->uri = $uri;
-    }
-
-    public function enterNode(Node $node)
-    {
-        $this->nodeStack[] = $node;
-        $containerName = end($this->nameStack);
-
-        // If we enter a named node, push its name onto name stack.
-        // Else push the current name onto stack.
-        if (!empty($node->name) && (is_string($node->name) || method_exists($node->name, '__toString')) && !empty((string)$node->name)) {
-            if (empty($containerName)) {
-                $this->nameStack[] = (string)$node->name;
-            } else if ($node instanceof Node\Stmt\ClassMethod) {
-                $this->nameStack[] = $containerName . '::' . (string)$node->name;
-            } else {
-                $this->nameStack[] = $containerName . '\\' . (string)$node->name;
-            }
-        } else {
-            $this->nameStack[] = $containerName;
-            // We are not interested in unnamed nodes, return
-            return;
-        }
-
-        $class = get_class($node);
-        if (!isset(self::NODE_SYMBOL_KIND_MAP[$class])) {
-            return;
-        }
-
-        // if we enter a method or function, increase the function counter
-        if ($node instanceof Node\Stmt\Function_ || $node instanceof Node\Stmt\ClassMethod) {
-            $this->functionCount++;
-        }
-
-        $kind = self::NODE_SYMBOL_KIND_MAP[$class];
-
-        // exclude non-global variable symbols.
-        if ($kind === SymbolKind::VARIABLE && $this->functionCount > 0) {
-            return;
-        }
-
-        $symbol = new SymbolInformation();
-        $symbol->kind = $kind;
-        $symbol->name = (string)$node->name;
-        $symbol->location = new Location(
-            $this->uri,
-            new Range(
-                new Position($node->getAttribute('startLine') - 1, $node->getAttribute('startColumn') - 1),
-                new Position($node->getAttribute('endLine') - 1, $node->getAttribute('endColumn'))
-            )
-        );
-        $symbol->containerName = $containerName;
-        $this->symbols[] = $symbol;
-    }
-
-    public function leaveNode(Node $node)
-    {
-        array_pop($this->nodeStack);
-        array_pop($this->nameStack);
-
-        // if we leave a method or function, decrease the function counter
-        if ($node instanceof Node\Stmt\Function_ || $node instanceof Node\Stmt\ClassMethod) {
-            $this->functionCount--;
-        }
-    }
-}
diff --git a/tests/LanguageServerTest.php b/tests/LanguageServerTest.php
index 7d82c23..521d602 100644
--- a/tests/LanguageServerTest.php
+++ b/tests/LanguageServerTest.php
@@ -34,7 +34,7 @@ class LanguageServerTest extends TestCase
                 'hoverProvider' => null,
                 'completionProvider' => null,
                 'signatureHelpProvider' => null,
-                'definitionProvider' => null,
+                'definitionProvider' => true,
                 'referencesProvider' => null,
                 'documentHighlightProvider' => null,
                 'workspaceSymbolProvider' => true,
diff --git a/tests/NodeVisitor/DefinitionCollectorTest.php b/tests/NodeVisitor/DefinitionCollectorTest.php
new file mode 100644
index 0000000..cbd82f2
--- /dev/null
+++ b/tests/NodeVisitor/DefinitionCollectorTest.php
@@ -0,0 +1,52 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\Tests\Server\TextDocument;
+
+use PHPUnit\Framework\TestCase;
+use PhpParser\{ParserFactory, NodeTraverser, Node};
+use PhpParser\NodeVisitor\NameResolver;
+use LanguageServer\{LanguageClient, Project, PhpDocument};
+use LanguageServer\Tests\MockProtocolStream;
+use LanguageServer\NodeVisitor\{ReferencesAdder, DefinitionCollector};
+
+class DefinitionCollectorTest extends TestCase
+{
+    public function test()
+    {
+        $client = new LanguageClient(new MockProtocolStream());
+        $project = new Project($client);
+        $parser = (new ParserFactory)->create(ParserFactory::PREFER_PHP7);
+        $document = new PhpDocument('whatever', $project, $client, $parser);
+        $traverser = new NodeTraverser;
+        $traverser->addVisitor(new NameResolver);
+        $traverser->addVisitor(new ReferencesAdder($document));
+        $definitionCollector = new DefinitionCollector;
+        $traverser->addVisitor($definitionCollector);
+        $stmts = $parser->parse(file_get_contents(__DIR__ . '/../../fixtures/symbols.php'));
+        $traverser->traverse($stmts);
+        $defs = $definitionCollector->definitions;
+        $this->assertEquals([
+            'TestNamespace\\TEST_CONST',
+            'TestNamespace\\TestClass',
+            'TestNamespace\\TestClass::TEST_CLASS_CONST',
+            'TestNamespace\\TestClass::staticTestProperty',
+            'TestNamespace\\TestClass::testProperty',
+            'TestNamespace\\TestClass::staticTestMethod()',
+            'TestNamespace\\TestClass::testMethod()',
+            'TestNamespace\\TestTrait',
+            'TestNamespace\\TestInterface',
+            'TestNamespace\\test_function()'
+        ], array_keys($defs));
+        $this->assertInstanceOf(Node\Const_::class, $defs['TestNamespace\\TEST_CONST']);
+        $this->assertInstanceOf(Node\Stmt\Class_::class, $defs['TestNamespace\\TestClass']);
+        $this->assertInstanceOf(Node\Const_::class, $defs['TestNamespace\\TestClass::TEST_CLASS_CONST']);
+        $this->assertInstanceOf(Node\Stmt\PropertyProperty::class, $defs['TestNamespace\\TestClass::staticTestProperty']);
+        $this->assertInstanceOf(Node\Stmt\PropertyProperty::class, $defs['TestNamespace\\TestClass::testProperty']);
+        $this->assertInstanceOf(Node\Stmt\ClassMethod::class, $defs['TestNamespace\\TestClass::staticTestMethod()']);
+        $this->assertInstanceOf(Node\Stmt\ClassMethod::class, $defs['TestNamespace\\TestClass::testMethod()']);
+        $this->assertInstanceOf(Node\Stmt\Trait_::class, $defs['TestNamespace\\TestTrait']);
+        $this->assertInstanceOf(Node\Stmt\Interface_::class, $defs['TestNamespace\\TestInterface']);
+        $this->assertInstanceOf(Node\Stmt\Function_::class, $defs['TestNamespace\\test_function()']);
+    }
+}
diff --git a/tests/PhpDocumentTest.php b/tests/PhpDocumentTest.php
index 465748a..93075fc 100644
--- a/tests/PhpDocumentTest.php
+++ b/tests/PhpDocumentTest.php
@@ -6,7 +6,9 @@ namespace LanguageServer\Tests\Server;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{LanguageClient, Project};
-use LanguageServer\Protocol\SymbolKind;
+use LanguageServer\NodeVisitor\NodeAtPositionFinder;
+use LanguageServer\Protocol\{SymbolKind, Position};
+use PhpParser\Node;
 
 class PhpDocumentTest extends TestCase
 {
@@ -23,48 +25,20 @@ class PhpDocumentTest extends TestCase
     public function testParsesVariableVariables()
     {
         $document = $this->project->getDocument('whatever');
-        
+
         $document->updateContent("<?php\n$\$a = 'foo';\n\$bar = 'baz';\n");
 
         $symbols = $document->getSymbols();
 
-        $this->assertEquals([
-            [
-                'name' => 'a',
-                'kind' => SymbolKind::VARIABLE,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 1,
-                            'character' => 0
-                        ],
-                        'end' => [
-                            'line' => 1,
-                            'character' => 3
-                        ]
-                    ]
-                ],
-                'containerName' => null
-            ],
-            [
-                'name' => 'bar',
-                'kind' => SymbolKind::VARIABLE,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 2,
-                            'character' => 0
-                        ],
-                        'end' => [
-                            'line' => 2,
-                            'character' => 4
-                        ]
-                    ]
-                ],
-                'containerName' => null
-            ]
-        ], json_decode(json_encode($symbols), true));
+        $this->assertEquals([], json_decode(json_encode($symbols), true));
+    }
+
+    public function testGetNodeAtPosition()
+    {
+        $document = $this->project->getDocument('whatever');
+        $document->updateContent("<?php\n$\$a = new SomeClass;");
+        $node = $document->getNodeAtPosition(new Position(1, 13));
+        $this->assertInstanceOf(Node\Name\FullyQualified::class, $node);
+        $this->assertEquals('SomeClass', (string)$node);
     }
 }
diff --git a/tests/ProjectTest.php b/tests/ProjectTest.php
index eb37fa7..5fb9afb 100644
--- a/tests/ProjectTest.php
+++ b/tests/ProjectTest.php
@@ -41,8 +41,9 @@ class ProjectTest extends TestCase
     {
         $this->project->getDocument('file:///document1.php')->updateContent("<?php\nfunction foo() {}\nfunction bar() {}\n");
         $this->project->getDocument('file:///document2.php')->updateContent("<?php\nfunction baz() {}\nfunction frob() {}\n");
+        $this->project->getDocument('invalid_file')->updateContent(file_get_contents(__DIR__ . '/../fixtures/invalid_file.php'));
 
-        $symbols = $this->project->findSymbols('ba');        
+        $symbols = $this->project->findSymbols('ba');
 
         $this->assertEquals([
             [
diff --git a/tests/Server/TextDocument/DefinitionTest.php b/tests/Server/TextDocument/DefinitionTest.php
new file mode 100644
index 0000000..948fb35
--- /dev/null
+++ b/tests/Server/TextDocument/DefinitionTest.php
@@ -0,0 +1,346 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\Tests\Server\TextDocument;
+
+use PHPUnit\Framework\TestCase;
+use LanguageServer\Tests\MockProtocolStream;
+use LanguageServer\{Server, LanguageClient, Project};
+use LanguageServer\Protocol\{TextDocumentIdentifier, Position};
+
+class DefinitionTest extends TestCase
+{
+    /**
+     * @var Server\TextDocument
+     */
+    private $textDocument;
+
+    public function setUp()
+    {
+        $client = new LanguageClient(new MockProtocolStream());
+        $project = new Project($client);
+        $this->textDocument = new Server\TextDocument($project, $client);
+        $project->getDocument('references')->updateContent(file_get_contents(__DIR__ . '/../../../fixtures/references.php'));
+        $project->getDocument('symbols')->updateContent(file_get_contents(__DIR__ . '/../../../fixtures/symbols.php'));
+        $project->getDocument('use')->updateContent(file_get_contents(__DIR__ . '/../../../fixtures/use.php'));
+    }
+
+    public function testDefinitionForClassLike()
+    {
+        // $obj = new TestClass();
+        // Get definition for TestClass
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(4, 16));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 6,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 21,
+                    'character' => 1
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForClassLikeUseStatement()
+    {
+        // use TestNamespace\TestClass;
+        // Get definition for TestClass
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('use'), new Position(4, 22));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 6,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 21,
+                    'character' => 1
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForClassLikeGroupUseStatement()
+    {
+        // use TestNamespace\{TestTrait, TestInterface};
+        // Get definition for TestInterface
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('use'), new Position(5, 37));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 28,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 31,
+                    'character' => 1
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForImplements()
+    {
+        // class TestClass implements TestInterface
+        // Get definition for TestInterface
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('symbols'), new Position(6, 33));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 28,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 31,
+                    'character' => 1
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForClassConstants()
+    {
+        // echo TestClass::TEST_CLASS_CONST;
+        // Get definition for TEST_CLASS_CONST
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(9, 21));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 8,
+                    'character' => 10
+                ],
+                'end' => [
+                    'line' => 8,
+                    'character' => 32
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForConstants()
+    {
+        // echo TEST_CONST;
+        // Get definition for TEST_CONST
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(23, 9));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 4,
+                    'character' => 6
+                ],
+                'end' => [
+                    'line' => 4,
+                    'character' => 22
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForStaticMethods()
+    {
+        // TestClass::staticTestMethod();
+        // Get definition for staticTestMethod
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(7, 20));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 12,
+                    'character' => 4
+                ],
+                'end' => [
+                    'line' => 15,
+                    'character' => 5
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForStaticProperties()
+    {
+        // echo TestClass::$staticTestProperty;
+        // Get definition for staticTestProperty
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(8, 25));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 9,
+                    'character' => 18
+                ],
+                'end' => [
+                    'line' => 9,
+                    'character' => 37
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForMethods()
+    {
+        // $obj->testMethod();
+        // Get definition for testMethod
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(5, 11));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 17,
+                    'character' => 4
+                ],
+                'end' => [
+                    'line' => 20,
+                    'character' => 5
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForProperties()
+    {
+        // echo $obj->testProperty;
+        // Get definition for testProperty
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(6, 18));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 10,
+                    'character' => 11
+                ],
+                'end' => [
+                    'line' => 10,
+                    'character' => 24
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForVariables()
+    {
+        // echo $var;
+        // Get definition for $var
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(13, 7));
+        $this->assertEquals([
+            'uri' => 'references',
+            'range' => [
+                'start' => [
+                    'line' => 12,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 12,
+                    'character' => 10
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForParamTypeHints()
+    {
+        // function whatever(TestClass $param) {
+        // Get definition for TestClass
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(15, 23));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 6,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 21,
+                    'character' => 1
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+    public function testDefinitionForReturnTypeHints()
+    {
+        // function whatever(TestClass $param) {
+        // Get definition for TestClass
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(15, 42));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 6,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 21,
+                    'character' => 1
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForParams()
+    {
+        // echo $param;
+        // Get definition for $param
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(16, 13));
+        $this->assertEquals([
+            'uri' => 'references',
+            'range' => [
+                'start' => [
+                    'line' => 15,
+                    'character' => 18
+                ],
+                'end' => [
+                    'line' => 15,
+                    'character' => 34
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForUsedVariables()
+    {
+        // echo $var;
+        // Get definition for $var
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(20, 11));
+        $this->assertEquals([
+            'uri' => 'references',
+            'range' => [
+                'start' => [
+                    'line' => 19,
+                    'character' => 22
+                ],
+                'end' => [
+                    'line' => 19,
+                    'character' => 26
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+
+    public function testDefinitionForFunctions()
+    {
+        // test_function();
+        // Get definition for test_function
+        $result = $this->textDocument->definition(new TextDocumentIdentifier('references'), new Position(10, 4));
+        $this->assertEquals([
+            'uri' => 'symbols',
+            'range' => [
+                'start' => [
+                    'line' => 33,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => 36,
+                    'character' => 1
+                ]
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+}
diff --git a/tests/Server/TextDocument/DidChangeTest.php b/tests/Server/TextDocument/DidChangeTest.php
new file mode 100644
index 0000000..081978f
--- /dev/null
+++ b/tests/Server/TextDocument/DidChangeTest.php
@@ -0,0 +1,38 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\Tests\Server\TextDocument;
+
+use PHPUnit\Framework\TestCase;
+use LanguageServer\Tests\MockProtocolStream;
+use LanguageServer\{Server, Client, LanguageClient, Project};
+use LanguageServer\Protocol\{
+    TextDocumentIdentifier,
+    TextDocumentItem,
+    VersionedTextDocumentIdentifier,
+    TextDocumentContentChangeEvent,
+    Range,
+    Position
+};
+
+class DidChangeTest extends TestCase
+{
+    public function test()
+    {
+        $client = new LanguageClient(new MockProtocolStream());
+        $project = new Project($client);
+        $textDocument = new Server\TextDocument($project, $client);
+        $phpDocument = $project->getDocument('whatever');
+        $phpDocument->updateContent("<?php\necho 'Hello, World'\n");
+
+        $identifier = new VersionedTextDocumentIdentifier('whatever');
+        $changeEvent = new TextDocumentContentChangeEvent();
+        $changeEvent->range = new Range(new Position(0, 0), new Position(9999, 9999));
+        $changeEvent->rangeLength = 9999;
+        $changeEvent->text = "<?php\necho 'Goodbye, World'\n";
+
+        $textDocument->didChange($identifier, [$changeEvent]);
+
+        $this->assertEquals("<?php\necho 'Goodbye, World'\n", $phpDocument->getContent());
+    }
+}
diff --git a/tests/Server/TextDocument/DocumentSymbolTest.php b/tests/Server/TextDocument/DocumentSymbolTest.php
new file mode 100644
index 0000000..e5edfe7
--- /dev/null
+++ b/tests/Server/TextDocument/DocumentSymbolTest.php
@@ -0,0 +1,213 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\Tests\Server\TextDocument;
+
+use PHPUnit\Framework\TestCase;
+use LanguageServer\Tests\MockProtocolStream;
+use LanguageServer\{Server, LanguageClient, Project};
+use LanguageServer\Protocol\{TextDocumentIdentifier, SymbolKind};
+
+class DocumentSymbolTest extends TestCase
+{
+    /**
+     * @var Server\TextDocument
+     */
+    private $textDocument;
+
+    public function setUp()
+    {
+        $client = new LanguageClient(new MockProtocolStream());
+        $project = new Project($client);
+        $this->textDocument = new Server\TextDocument($project, $client);
+        $project->getDocument('symbols')->updateContent(file_get_contents(__DIR__ . '/../../../fixtures/symbols.php'));
+    }
+
+    public function test()
+    {
+        // Request symbols
+        $result = $this->textDocument->documentSymbol(new TextDocumentIdentifier('symbols'));
+        $this->assertEquals([
+            [
+                'name' => 'TEST_CONST',
+                'kind' => SymbolKind::CONSTANT,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 4,
+                            'character' => 6
+                        ],
+                        'end' => [
+                            'line' => 4,
+                            'character' => 22
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace'
+            ],
+            [
+                'name' => 'TestClass',
+                'kind' => SymbolKind::CLASS_,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 6,
+                            'character' => 0
+                        ],
+                        'end' => [
+                            'line' => 21,
+                            'character' => 1
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace'
+            ],
+            [
+                'name' => 'TEST_CLASS_CONST',
+                'kind' => SymbolKind::CONSTANT,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 8,
+                            'character' => 10
+                        ],
+                        'end' => [
+                            'line' => 8,
+                            'character' => 32
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace\\TestClass'
+            ],
+            [
+                'name' => 'staticTestProperty',
+                'kind' => SymbolKind::PROPERTY,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 9,
+                            'character' => 18
+                        ],
+                        'end' => [
+                            'line' => 9,
+                            'character' => 37
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace\\TestClass'
+            ],
+            [
+                'name' => 'testProperty',
+                'kind' => SymbolKind::PROPERTY,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 10,
+                            'character' => 11
+                        ],
+                        'end' => [
+                            'line' => 10,
+                            'character' => 24
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace\\TestClass'
+            ],
+            [
+                'name' => 'staticTestMethod',
+                'kind' => SymbolKind::METHOD,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 12,
+                            'character' => 4
+                        ],
+                        'end' => [
+                            'line' => 15,
+                            'character' => 5
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace\\TestClass'
+            ],
+            [
+                'name' => 'testMethod',
+                'kind' => SymbolKind::METHOD,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 17,
+                            'character' => 4
+                        ],
+                        'end' => [
+                            'line' => 20,
+                            'character' => 5
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace\\TestClass'
+            ],
+            [
+                'name' => 'TestTrait',
+                'kind' => SymbolKind::CLASS_,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 23,
+                            'character' => 0
+                        ],
+                        'end' => [
+                            'line' => 26,
+                            'character' => 1
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace'
+            ],
+            [
+                'name' => 'TestInterface',
+                'kind' => SymbolKind::INTERFACE,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 28,
+                            'character' => 0
+                        ],
+                        'end' => [
+                            'line' => 31,
+                            'character' => 1
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace'
+            ],
+            [
+                'name' => 'test_function',
+                'kind' => SymbolKind::FUNCTION,
+                'location' => [
+                    'uri' => 'symbols',
+                    'range' => [
+                        'start' => [
+                            'line' => 33,
+                            'character' => 0
+                        ],
+                        'end' => [
+                            'line' => 36,
+                            'character' => 1
+                        ]
+                    ]
+                ],
+                'containerName' => 'TestNamespace'
+            ]
+        ], json_decode(json_encode($result), true));
+    }
+}
diff --git a/tests/Server/TextDocument/FormattingTest.php b/tests/Server/TextDocument/FormattingTest.php
new file mode 100644
index 0000000..2dcc46e
--- /dev/null
+++ b/tests/Server/TextDocument/FormattingTest.php
@@ -0,0 +1,57 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\Tests\Server\TextDocument;
+
+use PHPUnit\Framework\TestCase;
+use LanguageServer\Tests\MockProtocolStream;
+use LanguageServer\{Server, Client, LanguageClient, Project};
+use LanguageServer\Protocol\{TextDocumentIdentifier, TextDocumentItem, FormattingOptions};
+
+class FormattingTest extends TestCase
+{
+    /**
+     * @var Server\TextDocument
+     */
+    private $textDocument;
+
+    public function setUp()
+    {
+        $client = new LanguageClient(new MockProtocolStream());
+        $project = new Project($client);
+        $this->textDocument = new Server\TextDocument($project, $client);
+    }
+
+    public function test()
+    {
+        $client = new LanguageClient(new MockProtocolStream());
+        $project = new Project($client);
+        $textDocument = new Server\TextDocument($project, $client);
+
+        // Trigger parsing of source
+        $textDocumentItem = new TextDocumentItem();
+        $textDocumentItem->uri = 'whatever';
+        $textDocumentItem->languageId = 'php';
+        $textDocumentItem->version = 1;
+        $textDocumentItem->text = file_get_contents(__DIR__ . '/../../../fixtures/format.php');
+        $textDocument->didOpen($textDocumentItem);
+
+        // how code should look after formatting
+        $expected = file_get_contents(__DIR__ . '/../../../fixtures/format_expected.php');
+        // Request formatting
+        $result = $textDocument->formatting(new TextDocumentIdentifier('whatever'), new FormattingOptions());
+        $this->assertEquals([0 => [
+            'range' => [
+                'start' => [
+                    'line' => 0,
+                    'character' => 0
+                ],
+                'end' => [
+                    'line' => PHP_INT_MAX,
+                    'character' => PHP_INT_MAX
+                ]
+            ],
+            'newText' => $expected
+        ]], json_decode(json_encode($result), true));
+    }
+}
diff --git a/tests/Server/TextDocument/ParseErrorsTest.php b/tests/Server/TextDocument/ParseErrorsTest.php
new file mode 100644
index 0000000..24d155c
--- /dev/null
+++ b/tests/Server/TextDocument/ParseErrorsTest.php
@@ -0,0 +1,73 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\Tests\Server\TextDocument;
+
+use PHPUnit\Framework\TestCase;
+use LanguageServer\Tests\MockProtocolStream;
+use LanguageServer\{Server, Client, LanguageClient, Project};
+use LanguageServer\Protocol\{TextDocumentIdentifier, TextDocumentItem, DiagnosticSeverity};
+
+class ParseErrorsTest extends TestCase
+{
+    /**
+     * @var Server\TextDocument
+     */
+    private $textDocument;
+
+    public function setUp()
+    {
+        $client = new LanguageClient(new MockProtocolStream());
+        $project = new Project($client);
+        $this->textDocument = new Server\TextDocument($project, $client);
+    }
+
+    public function testParseErrorsArePublishedAsDiagnostics()
+    {
+        $args = null;
+        $client = new LanguageClient(new MockProtocolStream());
+        $client->textDocument = new class($args) extends Client\TextDocument {
+            private $args;
+            public function __construct(&$args)
+            {
+                parent::__construct(new MockProtocolStream());
+                $this->args = &$args;
+            }
+            public function publishDiagnostics(string $uri, array $diagnostics)
+            {
+                $this->args = func_get_args();
+            }
+        };
+
+        $project = new Project($client);
+
+        $textDocument = new Server\TextDocument($project, $client);
+
+        // Trigger parsing of source
+        $textDocumentItem = new TextDocumentItem();
+        $textDocumentItem->uri = 'whatever';
+        $textDocumentItem->languageId = 'php';
+        $textDocumentItem->version = 1;
+        $textDocumentItem->text = file_get_contents(__DIR__ . '/../../../fixtures/invalid_file.php');
+        $textDocument->didOpen($textDocumentItem);
+        $this->assertEquals([
+            'whatever',
+            [[
+                'range' => [
+                    'start' => [
+                        'line' => 2,
+                        'character' => 10
+                    ],
+                    'end' => [
+                        'line' => 2,
+                        'character' => 15
+                    ]
+                ],
+                'severity' => DiagnosticSeverity::ERROR,
+                'code' => null,
+                'source' => 'php',
+                'message' => "Syntax error, unexpected T_CLASS, expecting T_STRING"
+            ]]
+        ], json_decode(json_encode($args), true));
+    }
+}
diff --git a/tests/Server/TextDocumentTest.php b/tests/Server/TextDocumentTest.php
deleted file mode 100644
index 746ded6..0000000
--- a/tests/Server/TextDocumentTest.php
+++ /dev/null
@@ -1,241 +0,0 @@
-<?php
-declare(strict_types = 1);
-
-namespace LanguageServer\Tests\Server;
-
-use PHPUnit\Framework\TestCase;
-use LanguageServer\Tests\MockProtocolStream;
-use LanguageServer\{Server, Client, LanguageClient, Project, PhpDocument};
-use LanguageServer\Protocol\{TextDocumentItem, TextDocumentIdentifier, SymbolKind, DiagnosticSeverity, FormattingOptions, VersionedTextDocumentIdentifier, TextDocumentContentChangeEvent, Range, Position};
-use AdvancedJsonRpc\{Request as RequestBody, Response as ResponseBody};
-
-class TextDocumentTest extends TestCase
-{
-    public function testDocumentSymbol()
-    {
-        $client = new LanguageClient(new MockProtocolStream());
-        $project = new Project($client);
-        $textDocument = new Server\TextDocument($project, $client);
-        // Trigger parsing of source
-        $textDocumentItem = new TextDocumentItem();
-        $textDocumentItem->uri = 'whatever';
-        $textDocumentItem->languageId = 'php';
-        $textDocumentItem->version = 1;
-        $textDocumentItem->text = file_get_contents(__DIR__ . '/../../fixtures/symbols.php');
-        $textDocument->didOpen($textDocumentItem);
-        // Request symbols
-        $result = $textDocument->documentSymbol(new TextDocumentIdentifier('whatever'));
-        $this->assertEquals([
-            [
-                'name' => 'TestNamespace',
-                'kind' => SymbolKind::NAMESPACE,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 2,
-                            'character' => 0
-                        ],
-                        'end' => [
-                            'line' => 2,
-                            'character' => 24
-                        ]
-                    ]
-                ],
-                'containerName' => null
-            ],
-            [
-                'name' => 'TestClass',
-                'kind' => SymbolKind::CLASS_,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 4,
-                            'character' => 0
-                        ],
-                        'end' => [
-                            'line' => 12,
-                            'character' => 1
-                        ]
-                    ]
-                ],
-                'containerName' => 'TestNamespace'
-            ],
-            [
-                'name' => 'testProperty',
-                'kind' => SymbolKind::PROPERTY,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 6,
-                            'character' => 11
-                        ],
-                        'end' => [
-                            'line' => 6,
-                            'character' => 24
-                        ]
-                    ]
-                ],
-                'containerName' => 'TestNamespace\\TestClass'
-            ],
-            [
-                'name' => 'testMethod',
-                'kind' => SymbolKind::METHOD,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 8,
-                            'character' => 4
-                        ],
-                        'end' => [
-                            'line' => 11,
-                            'character' => 5
-                        ]
-                    ]
-                ],
-                'containerName' => 'TestNamespace\\TestClass'
-            ],
-            [
-                'name' => 'TestTrait',
-                'kind' => SymbolKind::CLASS_,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 14,
-                            'character' => 0
-                        ],
-                        'end' => [
-                            'line' => 17,
-                            'character' => 1
-                        ]
-                    ]
-                ],
-                'containerName' => 'TestNamespace'
-            ],
-            [
-                'name' => 'TestInterface',
-                'kind' => SymbolKind::INTERFACE,
-                'location' => [
-                    'uri' => 'whatever',
-                    'range' => [
-                        'start' => [
-                            'line' => 19,
-                            'character' => 0
-                        ],
-                        'end' => [
-                            'line' => 22,
-                            'character' => 1
-                        ]
-                    ]
-                ],
-                'containerName' => 'TestNamespace'
-            ]
-        ], json_decode(json_encode($result), true));
-    }
-
-    public function testParseErrorsArePublishedAsDiagnostics()
-    {
-        $args = null;
-        $client = new LanguageClient(new MockProtocolStream());
-        $client->textDocument = new class($args) extends Client\TextDocument {
-            private $args;
-            public function __construct(&$args)
-            {
-                parent::__construct(new MockProtocolStream());
-                $this->args = &$args;
-            }
-            public function publishDiagnostics(string $uri, array $diagnostics)
-            {
-                $this->args = func_get_args();
-            }
-        };
-
-        $project = new Project($client);
-
-        $textDocument = new Server\TextDocument($project, $client);
-
-        // Trigger parsing of source
-        $textDocumentItem = new TextDocumentItem();
-        $textDocumentItem->uri = 'whatever';
-        $textDocumentItem->languageId = 'php';
-        $textDocumentItem->version = 1;
-        $textDocumentItem->text = file_get_contents(__DIR__ . '/../../fixtures/invalid_file.php');
-        $textDocument->didOpen($textDocumentItem);
-        $this->assertEquals([
-            'whatever',
-            [[
-                'range' => [
-                    'start' => [
-                        'line' => 2,
-                        'character' => 10
-                    ],
-                    'end' => [
-                        'line' => 2,
-                        'character' => 15
-                    ]
-                ],
-                'severity' => DiagnosticSeverity::ERROR,
-                'code' => null,
-                'source' => 'php',
-                'message' => "Syntax error, unexpected T_CLASS, expecting T_STRING"
-            ]]
-        ], json_decode(json_encode($args), true));
-    }
-
-    public function testFormatting()
-    {
-        $client =  new LanguageClient(new MockProtocolStream());
-        $project = new Project($client);
-        $textDocument = new Server\TextDocument($project, $client);
-
-        // Trigger parsing of source
-        $textDocumentItem = new TextDocumentItem();
-        $textDocumentItem->uri = 'whatever';
-        $textDocumentItem->languageId = 'php';
-        $textDocumentItem->version = 1;
-        $textDocumentItem->text = file_get_contents(__DIR__ . '/../../fixtures/format.php');
-        $textDocument->didOpen($textDocumentItem);
-
-        // how code should look after formatting
-        $expected = file_get_contents(__DIR__ . '/../../fixtures/format_expected.php');
-        // Request formatting
-        $result = $textDocument->formatting(new TextDocumentIdentifier('whatever'), new FormattingOptions());
-        $this->assertEquals([0 => [
-            'range' => [
-                'start' => [
-                    'line' => 0,
-                    'character' => 0
-                ],
-                'end' => [
-                    'line' => PHP_INT_MAX,
-                    'character' => PHP_INT_MAX
-                ]
-            ],
-            'newText' => $expected
-        ]], json_decode(json_encode($result), true));
-    }
-
-    public function testDidChange()
-    {
-        $client =  new LanguageClient(new MockProtocolStream());
-        $project = new Project($client);
-        $textDocument = new Server\TextDocument($project, $client);
-
-        $phpDocument = $project->getDocument('whatever');
-        $phpDocument->updateContent("<?php\necho 'Hello, World'\n");
-
-        $identifier = new VersionedTextDocumentIdentifier('whatever');
-        $changeEvent = new TextDocumentContentChangeEvent();
-        $changeEvent->range = new Range(new Position(0,0), new Position(9999,9999));
-        $changeEvent->rangeLength = 9999;
-        $changeEvent->text = "<?php\necho 'Goodbye, World'\n";
-
-        $textDocument->didChange($identifier, [$changeEvent]);
-
-        $this->assertEquals("<?php\necho 'Goodbye, World'\n", $phpDocument->getContent());
-    }
-}