diff --git a/docs/type-system/index.md b/docs/type-system/index.md
index e4a41f1..dc0c2bd 100644
--- a/docs/type-system/index.md
+++ b/docs/type-system/index.md
@@ -26,7 +26,7 @@ $myType = new ObjectType([
 ]);
 ```
 
-Class per type, using inheritance:
+Class per type:
 ```php
 <?php
 namespace MyApp;
@@ -50,31 +50,6 @@ class MyType extends ObjectType
 }
 ```
 
-Class per type, using composition:
-```php
-<?php
-namespace MyApp;
-
-use GraphQL\Type\Definition\ObjectType;
-use GraphQL\Type\Definition\Type;
-use GraphQL\Type\DefinitionContainer;
-
-class MyType implements DefinitionContainer
-{
-    private $definition;
-
-    public function getDefinition()
-    {
-        return $this->definition ?: ($this->definition = new ObjectType([
-            'name' => 'MyType',
-            'fields' => [
-                'id' => Type::id()
-            ]
-        ]));
-    }
-}
-```
-
 You can also mix-and-match styles for convenience. For example:
 ```php
 <?php
diff --git a/docs/type-system/scalar-types.md b/docs/type-system/scalar-types.md
index 0c51a9f..bd0ac1d 100644
--- a/docs/type-system/scalar-types.md
+++ b/docs/type-system/scalar-types.md
@@ -35,7 +35,7 @@ or hardcoded in source code) to **serialized** representation included in respon
 Those cases are covered by methods `serialize`, `parseValue` and `parseLiteral` of abstract `ScalarType` 
 class respectively.
 
-Here is an example of simple `Email` type (using inheritance):
+Here is an example of simple `Email` type:
 
 ```php
 <?php
@@ -109,30 +109,6 @@ class EmailType extends ScalarType
 }
 ```
 
-Same example, using composition over inheritance:
-```php
-<?php
-namespace MyApp;
-
-use GraphQL\Type\DefinitionContainer;
-use GraphQL\Type\Definition\CustomScalarType;
-
-class EmailType implements DefinitionContainer
-{
-    private $definition;
-
-    public function getDefinition()
-    {
-        return $this->definition ?: ($this->definition = new CustomScalarType([
-            'name' => 'Email',
-            'serialize' => function($value) {/* See function body above */},
-            'parseValue' => function($value) {/* See function body above */},
-            'parseLiteral' => function($valueNode) {/* See function body above */},
-        ]));
-    }
-}
-```
-
 Or with inline style:
 
 ```php
diff --git a/examples/01-blog/Blog/Type/BaseType.php b/examples/01-blog/Blog/Type/BaseType.php
deleted file mode 100644
index af14eea..0000000
--- a/examples/01-blog/Blog/Type/BaseType.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-namespace GraphQL\Examples\Blog\Type;
-
-use GraphQL\Type\Definition\Type;
-use GraphQL\Type\DefinitionContainer;
-
-abstract class BaseType implements DefinitionContainer
-{
-    // Base class to reduce boilerplate for those who prefer own clean hierarchy of classes
-    // (and avoids extending GraphQL classes directly)
-
-    /**
-     * @var Type
-     */
-    protected $definition;
-
-    /**
-     * @return Type
-     */
-    public function getDefinition()
-    {
-        return $this->definition;
-    }
-}
diff --git a/examples/01-blog/Blog/Type/CommentType.php b/examples/01-blog/Blog/Type/CommentType.php
index b3cdeac..b89aa54 100644
--- a/examples/01-blog/Blog/Type/CommentType.php
+++ b/examples/01-blog/Blog/Type/CommentType.php
@@ -8,12 +8,11 @@ use GraphQL\Examples\Blog\Types;
 use GraphQL\Type\Definition\ObjectType;
 use GraphQL\Type\Definition\ResolveInfo;
 
-class CommentType extends BaseType
+class CommentType extends ObjectType
 {
     public function __construct()
     {
-        // Option #1: using composition over inheritance to define type, see ImageType for inheritance example
-        $this->definition = new ObjectType([
+        $config = [
             'name' => 'Comment',
             'fields' => function() {
                 return [
@@ -43,7 +42,8 @@ class CommentType extends BaseType
                     return $value->{$info->fieldName};
                 }
             }
-        ]);
+        ];
+        parent::__construct($config);
     }
 
     public function author(Comment $comment)
diff --git a/examples/01-blog/Blog/Type/Enum/ContentFormatEnum.php b/examples/01-blog/Blog/Type/Enum/ContentFormatEnum.php
index 162d457..8825247 100644
--- a/examples/01-blog/Blog/Type/Enum/ContentFormatEnum.php
+++ b/examples/01-blog/Blog/Type/Enum/ContentFormatEnum.php
@@ -1,20 +1,19 @@
 <?php
 namespace GraphQL\Examples\Blog\Type\Enum;
 
-use GraphQL\Examples\Blog\Type\BaseType;
 use GraphQL\Type\Definition\EnumType;
 
-class ContentFormatEnum extends BaseType
+class ContentFormatEnum extends EnumType
 {
     const FORMAT_TEXT = 'TEXT';
     const FORMAT_HTML = 'HTML';
 
     public function __construct()
     {
-        // Option #1: Define type using composition over inheritance, see ImageSizeEnumType for inheritance option
-        $this->definition = new EnumType([
+        $config = [
             'name' => 'ContentFormatEnum',
             'values' => [self::FORMAT_TEXT, self::FORMAT_HTML]
-        ]);
+        ];
+        parent::__construct($config);
     }
 }
diff --git a/examples/01-blog/Blog/Type/Enum/ImageSizeEnumType.php b/examples/01-blog/Blog/Type/Enum/ImageSizeEnumType.php
index 384fb5e..5e744a6 100644
--- a/examples/01-blog/Blog/Type/Enum/ImageSizeEnumType.php
+++ b/examples/01-blog/Blog/Type/Enum/ImageSizeEnumType.php
@@ -8,7 +8,6 @@ class ImageSizeEnumType extends EnumType
 {
     public function __construct()
     {
-        // Option #2: Define enum type using inheritance
         $config = [
             // Note: 'name' option is not needed in this form - it will be inferred from className
             'values' => [
diff --git a/examples/01-blog/Blog/Type/ImageType.php b/examples/01-blog/Blog/Type/ImageType.php
index 90b8555..aef9bff 100644
--- a/examples/01-blog/Blog/Type/ImageType.php
+++ b/examples/01-blog/Blog/Type/ImageType.php
@@ -11,7 +11,6 @@ class ImageType extends ObjectType
 {
     public function __construct()
     {
-        // Option #2: define type using inheritance, see any other object type for compositional example
         $config = [
             'name' => 'ImageType',
             'fields' => [
diff --git a/examples/01-blog/Blog/Type/NodeType.php b/examples/01-blog/Blog/Type/NodeType.php
index 7a60288..d3be9ed 100644
--- a/examples/01-blog/Blog/Type/NodeType.php
+++ b/examples/01-blog/Blog/Type/NodeType.php
@@ -7,21 +7,21 @@ use GraphQL\Examples\Blog\Data\Image;
 use GraphQL\Examples\Blog\Types;
 use GraphQL\Type\Definition\InterfaceType;
 
-class NodeType extends BaseType
+class NodeType extends InterfaceType
 {
     public function __construct()
     {
-        // Option #1: using composition over inheritance to define type, see ImageType for inheritance example
-        $this->definition = new InterfaceType([
+        $config = [
             'name' => 'Node',
             'fields' => [
                 'id' => Types::id()
             ],
-            'resolveType' => [$this, 'resolveType']
-        ]);
+            'resolveType' => [$this, 'resolveNodeType']
+        ];
+        parent::__construct($config);
     }
 
-    public function resolveType($object, Types $types)
+    public function resolveNodeType($object)
     {
         if ($object instanceof User) {
             return Types::user();
diff --git a/examples/01-blog/Blog/Type/QueryType.php b/examples/01-blog/Blog/Type/QueryType.php
index 0e7268e..ff85577 100644
--- a/examples/01-blog/Blog/Type/QueryType.php
+++ b/examples/01-blog/Blog/Type/QueryType.php
@@ -8,12 +8,11 @@ use GraphQL\Type\Definition\ObjectType;
 use GraphQL\Type\Definition\ResolveInfo;
 use GraphQL\Type\Definition\Type;
 
-class QueryType extends BaseType
+class QueryType extends ObjectType
 {
     public function __construct()
     {
-        // Option #1: using composition over inheritance to define type, see ImageType for inheritance example
-        $this->definition = new ObjectType([
+        $config = [
             'name' => 'Query',
             'fields' => [
                 'user' => [
@@ -61,7 +60,8 @@ class QueryType extends BaseType
             'resolveField' => function($val, $args, $context, ResolveInfo $info) {
                 return $this->{$info->fieldName}($val, $args, $context, $info);
             }
-        ]);
+        ];
+        parent::__construct($config);
     }
 
     public function user($rootValue, $args)
diff --git a/examples/01-blog/Blog/Type/Scalar/EmailType.php b/examples/01-blog/Blog/Type/Scalar/EmailType.php
index 0eea0dd..9c1f15e 100644
--- a/examples/01-blog/Blog/Type/Scalar/EmailType.php
+++ b/examples/01-blog/Blog/Type/Scalar/EmailType.php
@@ -2,21 +2,19 @@
 namespace GraphQL\Examples\Blog\Type\Scalar;
 
 use GraphQL\Error\Error;
-use GraphQL\Examples\Blog\Type\BaseType;
 use GraphQL\Language\AST\StringValueNode;
 use GraphQL\Type\Definition\CustomScalarType;
 use GraphQL\Utils;
 
-class EmailType extends BaseType
+class EmailType
 {
-    public function __construct()
+    public static function create()
     {
-        // Option #1: define scalar types using composition (see UrlType fo option #2 using inheritance)
-        $this->definition = new CustomScalarType([
+        return new CustomScalarType([
             'name' => 'Email',
-            'serialize' => [$this, 'serialize'],
-            'parseValue' => [$this, 'parseValue'],
-            'parseLiteral' => [$this, 'parseLiteral'],
+            'serialize' => [__CLASS__, 'serialize'],
+            'parseValue' => [__CLASS__, 'parseValue'],
+            'parseLiteral' => [__CLASS__, 'parseLiteral'],
         ]);
     }
 
@@ -26,7 +24,7 @@ class EmailType extends BaseType
      * @param string $value
      * @return string
      */
-    public function serialize($value)
+    public static function serialize($value)
     {
         // Assuming internal representation of email is always correct:
         return $value;
@@ -42,7 +40,7 @@ class EmailType extends BaseType
      * @param mixed $value
      * @return mixed
      */
-    public function parseValue($value)
+    public static function parseValue($value)
     {
         if (!filter_var($value, FILTER_VALIDATE_EMAIL)) {
             throw new \UnexpectedValueException("Cannot represent value as email: " . Utils::printSafe($value));
@@ -57,7 +55,7 @@ class EmailType extends BaseType
      * @return string
      * @throws Error
      */
-    public function parseLiteral($valueNode)
+    public static function parseLiteral($valueNode)
     {
         // Note: throwing GraphQL\Error\Error vs \UnexpectedValueException to benefit from GraphQL
         // error location in query:
diff --git a/examples/01-blog/Blog/Type/Scalar/UrlType.php b/examples/01-blog/Blog/Type/Scalar/UrlType.php
index f9169e2..f565096 100644
--- a/examples/01-blog/Blog/Type/Scalar/UrlType.php
+++ b/examples/01-blog/Blog/Type/Scalar/UrlType.php
@@ -9,8 +9,6 @@ use GraphQL\Utils;
 
 class UrlType extends ScalarType
 {
-    // Option #2: Displays scalar type defined using inheritance. See EmailType for definition via composition
-
     /**
      * Serializes an internal value to include in a response.
      *
diff --git a/examples/01-blog/Blog/Type/SearchResultType.php b/examples/01-blog/Blog/Type/SearchResultType.php
index b1df78a..d832a26 100644
--- a/examples/01-blog/Blog/Type/SearchResultType.php
+++ b/examples/01-blog/Blog/Type/SearchResultType.php
@@ -6,12 +6,11 @@ use GraphQL\Examples\Blog\Data\User;
 use GraphQL\Examples\Blog\Types;
 use GraphQL\Type\Definition\UnionType;
 
-class SearchResultType extends BaseType
+class SearchResultType extends UnionType
 {
     public function __construct()
     {
-        // Option #1: using composition over inheritance to define type, see ImageType for inheritance example
-        $this->definition = new UnionType([
+        $config = [
             'name' => 'SearchResultType',
             'types' => function() {
                 return [
@@ -26,6 +25,7 @@ class SearchResultType extends BaseType
                     return Types::user();
                 }
             }
-        ]);
+        ];
+        parent::__construct($config);
     }
 }
diff --git a/examples/01-blog/Blog/Type/StoryType.php b/examples/01-blog/Blog/Type/StoryType.php
index d4ee8e2..38cf73f 100644
--- a/examples/01-blog/Blog/Type/StoryType.php
+++ b/examples/01-blog/Blog/Type/StoryType.php
@@ -13,7 +13,7 @@ use GraphQL\Type\Definition\ResolveInfo;
  * Class StoryType
  * @package GraphQL\Examples\Social\Type
  */
-class StoryType extends BaseType
+class StoryType extends ObjectType
 {
     const EDIT = 'EDIT';
     const DELETE = 'DELETE';
@@ -23,8 +23,7 @@ class StoryType extends BaseType
 
     public function __construct()
     {
-        // Option #1: using composition over inheritance to define type, see ImageType for inheritance example
-        $this->definition = new ObjectType([
+        $config = [
             'name' => 'Story',
             'fields' => function() {
                 return [
@@ -83,7 +82,8 @@ class StoryType extends BaseType
                     return $value->{$info->fieldName};
                 }
             }
-        ]);
+        ];
+        parent::__construct($config);
     }
 
     public function author(Story $story)
diff --git a/examples/01-blog/Blog/Type/UserType.php b/examples/01-blog/Blog/Type/UserType.php
index 0a7da72..347da46 100644
--- a/examples/01-blog/Blog/Type/UserType.php
+++ b/examples/01-blog/Blog/Type/UserType.php
@@ -8,12 +8,11 @@ use GraphQL\Examples\Blog\Types;
 use GraphQL\Type\Definition\ObjectType;
 use GraphQL\Type\Definition\ResolveInfo;
 
-class UserType extends BaseType
+class UserType extends ObjectType
 {
     public function __construct()
     {
-        // Option #1: using composition over inheritance to define type, see ImageType for inheritance example
-        $this->definition = new ObjectType([
+        $config = [
             'name' => 'User',
             'description' => 'Our blog authors',
             'fields' => function() {
@@ -52,7 +51,8 @@ class UserType extends BaseType
                     return $value->{$info->fieldName};
                 }
             }
-        ]);
+        ];
+        parent::__construct($config);
     }
 
     public function photo(User $user, $args)
diff --git a/examples/01-blog/Blog/Types.php b/examples/01-blog/Blog/Types.php
index da0d996..7ffc657 100644
--- a/examples/01-blog/Blog/Types.php
+++ b/examples/01-blog/Blog/Types.php
@@ -16,7 +16,6 @@ use GraphQL\Examples\Blog\Type\ImageType;
 use GraphQL\Type\Definition\ListOfType;
 use GraphQL\Type\Definition\NonNull;
 use GraphQL\Type\Definition\Type;
-use GraphQL\Type\DefinitionContainer;
 
 /**
  * Class Types
@@ -128,7 +127,7 @@ class Types
 
     public static function email()
     {
-        return self::$emailType ?: (self::$emailType = new EmailType());
+        return self::$emailType ?: (self::$emailType = EmailType::create());
     }
 
     /**
@@ -191,7 +190,7 @@ class Types
     }
 
     /**
-     * @param Type|DefinitionContainer $type
+     * @param Type $type
      * @return ListOfType
      */
     public static function listOf($type)
@@ -200,7 +199,7 @@ class Types
     }
 
     /**
-     * @param Type|DefinitionContainer $type
+     * @param Type $type
      * @return NonNull
      */
     public static function nonNull($type)
diff --git a/src/Executor/Executor.php b/src/Executor/Executor.php
index 0d87840..e0f9a2d 100644
--- a/src/Executor/Executor.php
+++ b/src/Executor/Executor.php
@@ -20,7 +20,6 @@ use GraphQL\Type\Definition\NonNull;
 use GraphQL\Type\Definition\ObjectType;
 use GraphQL\Type\Definition\ResolveInfo;
 use GraphQL\Type\Definition\Type;
-use GraphQL\Type\DefinitionContainer;
 use GraphQL\Type\Introspection;
 use GraphQL\Utils;
 
@@ -754,11 +753,6 @@ class Executor
             $runtimeType = $exeContext->schema->getType($runtimeType);
         }
 
-        // FIXME: Executor should never face with DefinitionContainer - it should be unwrapped in Schema
-        if ($runtimeType instanceof DefinitionContainer) {
-            $runtimeType = $runtimeType->getDefinition();
-        }
-
         if (!($runtimeType instanceof ObjectType)) {
             throw new Error(
                 "Abstract type {$returnType} must resolve to an Object type at runtime " .
diff --git a/src/Schema.php b/src/Schema.php
index b8c8a62..a1c527d 100644
--- a/src/Schema.php
+++ b/src/Schema.php
@@ -9,7 +9,6 @@ use GraphQL\Type\Definition\ObjectType;
 use GraphQL\Type\Definition\Type;
 use GraphQL\Type\Definition\UnionType;
 use GraphQL\Type\Definition\WrappingType;
-use GraphQL\Type\DefinitionContainer;
 use GraphQL\Type\Introspection;
 
 /**
@@ -114,18 +113,6 @@ class Schema
             'validate' => true
         ];
 
-        if ($config['query'] instanceof DefinitionContainer) {
-            $config['query'] = $config['query']->getDefinition();
-        }
-
-        if ($config['mutation'] instanceof DefinitionContainer) {
-            $config['mutation'] = $config['mutation']->getDefinition();
-        }
-
-        if ($config['subscription'] instanceof DefinitionContainer) {
-            $config['subscription'] = $config['subscription']->getDefinition();
-        }
-
         Utils::invariant(
             $config['query'] instanceof ObjectType,
             "Schema query must be Object Type but got: " . Utils::getVariableType($config['query'])
@@ -301,9 +288,6 @@ class Schema
         if (!$type) {
             return $this->typeMap;
         }
-        if ($type instanceof DefinitionContainer) {
-            $type = $type->getDefinition();
-        }
 
         if ($type instanceof WrappingType) {
             return $this->extractTypes($type->getWrappedType(true));
diff --git a/src/Type/Definition/Config.php b/src/Type/Definition/Config.php
index 0d1a171..bffef16 100644
--- a/src/Type/Definition/Config.php
+++ b/src/Type/Definition/Config.php
@@ -2,7 +2,6 @@
 namespace GraphQL\Type\Definition;
 
 use GraphQL\Error\InvariantViolation;
-use GraphQL\Type\DefinitionContainer;
 use GraphQL\Utils;
 
 /**
@@ -190,10 +189,6 @@ class Config
                 $err = 'Error in "'.$typeName.'" type definition: ' . "Each entry at '$pathStr' must be an array, but '%s' is '%s'";
 
                 foreach ($value as $arrKey => $arrValue) {
-                    if ($arrValue instanceof DefinitionContainer) {
-                        $arrValue = $arrValue->getDefinition();
-                    }
-
                     if (is_array($def->definition)) {
                         if ($def->flags & self::MAYBE_TYPE && $arrValue instanceof Type) {
                             $arrValue = ['type' => $arrValue];
@@ -226,10 +221,6 @@ class Config
                 return ; // Allow nulls for non-required fields
             }
 
-            if ($value instanceof DefinitionContainer) {
-                $value = $value->getDefinition();
-            }
-
             switch (true) {
                 case $def & self::ANY:
                     break;
diff --git a/src/Type/Definition/ListOfType.php b/src/Type/Definition/ListOfType.php
index f4f892f..4784e81 100644
--- a/src/Type/Definition/ListOfType.php
+++ b/src/Type/Definition/ListOfType.php
@@ -1,7 +1,6 @@
 <?php
 namespace GraphQL\Type\Definition;
 
-use GraphQL\Type\DefinitionContainer;
 use GraphQL\Utils;
 
 /**
@@ -16,12 +15,12 @@ class ListOfType extends Type implements WrappingType, OutputType, InputType
     public $ofType;
 
     /**
-     * @param callable|Type|DefinitionContainer $type
+     * @param callable|Type $type
      */
     public function __construct($type)
     {
         Utils::invariant(
-            $type instanceof Type || $type instanceof DefinitionContainer || is_callable($type),
+            $type instanceof Type || is_callable($type),
             'Expecting instance of GraphQL\Type\Definition\Type or callable returning instance of that class'
         );
 
diff --git a/src/Type/Definition/NonNull.php b/src/Type/Definition/NonNull.php
index 2e1c106..fe58634 100644
--- a/src/Type/Definition/NonNull.php
+++ b/src/Type/Definition/NonNull.php
@@ -1,8 +1,6 @@
 <?php
 namespace GraphQL\Type\Definition;
 
-use GraphQL\Type\DefinitionContainer;
-use GraphQL\Type\TypeKind;
 use GraphQL\Utils;
 
 /**
@@ -17,13 +15,13 @@ class NonNull extends Type implements WrappingType, OutputType, InputType
     private $ofType;
 
     /**
-     * @param callable|Type|DefinitionContainer $type
+     * @param callable|Type $type
      * @throws \Exception
      */
     public function __construct($type)
     {
         Utils::invariant(
-            $type instanceof Type || $type instanceof DefinitionContainer || is_callable($type),
+            $type instanceof Type || is_callable($type),
             'Expecting instance of GraphQL\Type\Definition\Type or callable returning instance of that class'
         );
         Utils::invariant(
diff --git a/src/Type/Definition/ObjectType.php b/src/Type/Definition/ObjectType.php
index cea5dea..4bcd153 100644
--- a/src/Type/Definition/ObjectType.php
+++ b/src/Type/Definition/ObjectType.php
@@ -1,7 +1,6 @@
 <?php
 namespace GraphQL\Type\Definition;
 use GraphQL\Error\InvariantViolation;
-use GraphQL\Type\DefinitionContainer;
 use GraphQL\Utils;
 
 
@@ -155,7 +154,7 @@ class ObjectType extends Type implements OutputType, CompositeType
     }
 
     /**
-     * @param InterfaceType|DefinitionContainer $iface
+     * @param InterfaceType $iface
      * @return bool
      */
     public function implementsInterface($iface)
diff --git a/src/Type/Definition/Type.php b/src/Type/Definition/Type.php
index 04a0e69..f1165f7 100644
--- a/src/Type/Definition/Type.php
+++ b/src/Type/Definition/Type.php
@@ -2,7 +2,6 @@
 namespace GraphQL\Type\Definition;
 
 use GraphQL\Error\InvariantViolation;
-use GraphQL\Type\DefinitionContainer;
 use GraphQL\Utils;
 
 /*
@@ -198,9 +197,6 @@ abstract class Type implements \JsonSerializable
             );
             $type = $type();
         }
-        if ($type instanceof DefinitionContainer) {
-            $type = $type->getDefinition();
-        }
 
         if (!$type instanceof Type) {
             throw new InvariantViolation(sprintf(
diff --git a/src/Type/Definition/UnionType.php b/src/Type/Definition/UnionType.php
index 7fce6bd..ec83914 100644
--- a/src/Type/Definition/UnionType.php
+++ b/src/Type/Definition/UnionType.php
@@ -1,7 +1,6 @@
 <?php
 namespace GraphQL\Type\Definition;
 
-use GraphQL\Type\DefinitionContainer;
 use GraphQL\Utils;
 
 /**
diff --git a/src/Type/DefinitionContainer.php b/src/Type/DefinitionContainer.php
deleted file mode 100644
index 6cabc5e..0000000
--- a/src/Type/DefinitionContainer.php
+++ /dev/null
@@ -1,15 +0,0 @@
-<?php
-namespace GraphQL\Type;
-use GraphQL\Type\Definition\Type;
-
-/**
- * Interface DefinitionContainer
- * @package GraphQL\Type
- */
-interface DefinitionContainer
-{
-    /**
-     * @return Type
-     */
-    public function getDefinition();
-}