diff --git a/src/ActivityPub.php b/src/ActivityPub.php
index b4b108f..978db0c 100644
--- a/src/ActivityPub.php
+++ b/src/ActivityPub.php
@@ -5,6 +5,7 @@
 namespace ActivityPub;
 
 use ActivityPub\Activities\AcceptHandler;
+use ActivityPub\Activities\AddHandler;
 use ActivityPub\Activities\CreateHandler;
 use ActivityPub\Activities\DeleteHandler;
 use ActivityPub\Activities\FollowHandler;
@@ -90,6 +91,7 @@ class ActivityPub
         $dispatcher->addSubscriber( $this->module->get( DeleteHandler::class ) );
         $dispatcher->addSubscriber( $this->module->get( FollowHandler::class ) );
         $dispatcher->addSubscriber( $this->module->get( AcceptHandler::class ) );
+        $dispatcher->addSubscriber( $this->module->get( AddHandler::class ) );
     }
 
     /**
diff --git a/src/Config/ActivityPubModule.php b/src/Config/ActivityPubModule.php
index 6debc2d..fdbefc6 100644
--- a/src/Config/ActivityPubModule.php
+++ b/src/Config/ActivityPubModule.php
@@ -5,6 +5,7 @@
 namespace ActivityPub\Config;
 
 use ActivityPub\Activities\AcceptHandler;
+use ActivityPub\Activities\AddHandler;
 use ActivityPub\Activities\CreateHandler;
 use ActivityPub\Activities\DeleteHandler;
 use ActivityPub\Activities\FollowHandler;
@@ -144,6 +145,10 @@ class ActivityPubModule
             ->addArgument( new Reference( ObjectsService::class ) )
             ->addArgument( new Reference( CollectionsService::class ) )
             ->addArgument( new Reference( ContextProvider::class ) );
+
+        $this->injector->register( AddHandler::class, AddHandler::class )
+            ->addArgument( new Reference( ObjectsService::class ) )
+            ->addArgument( new Reference( CollectionsService::class ) );
     }
 
     /**
diff --git a/test/Activities/AddHandlerTest.php b/test/Activities/AddHandlerTest.php
index 957d359..c57a95f 100644
--- a/test/Activities/AddHandlerTest.php
+++ b/test/Activities/AddHandlerTest.php
@@ -2,13 +2,154 @@
 
 namespace ActivityPub\Test\Activities;
 
+use ActivityPub\Activities\AddHandler;
+use ActivityPub\Activities\InboxActivityEvent;
+use ActivityPub\Activities\OutboxActivityEvent;
+use ActivityPub\Objects\CollectionsService;
+use ActivityPub\Objects\ObjectsService;
 use ActivityPub\Test\TestConfig\APTestCase;
+use ActivityPub\Test\TestUtils\TestActivityPubObject;
+use Symfony\Component\EventDispatcher\EventDispatcher;
+use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
 
 class AddHandlerTest extends APTestCase
 {
+    private static function getObjects()
+    {
+        return array(
+            'https://elsewhere.com/collections/1' => array(
+                'id' => 'https://elsewhere.com/collections/1',
+            ),
+            'https://example.com/collections/1' => array(
+                'id' => 'https://example.com/collections/1',
+            ),
+        );
+    }
+
     public function testHandleAdd()
     {
-        // TODO implement me
-        $this->assertTrue( false );
+        $testCases = array(
+            array(
+                'id' => 'basicTest',
+                'eventName' => InboxActivityEvent::NAME,
+                'event' => new InboxActivityEvent(
+                    array(
+                        'id' => 'https://elsewhere.com/adds/1',
+                        'type' => 'Add',
+                        'object' => array(
+                            'id' => 'https://elsewhere.com/notes/1',
+                        ),
+                        'target' => array(
+                            'id' => 'https://elsewhere.com/collections/1'
+                        )
+                    ),
+                    TestActivityPubObject::fromArray( array(
+                        'id' => 'https://example.com/actors/1',
+                    ) ),
+                    self::requestWithAttributes(
+                        'https://example.com/actors/1/inbox',
+                        array(
+                            'actor' => TestActivityPubObject::fromArray( array(
+                                'id' => 'https://elsewhere.com/actors/1'
+                            ) )
+                        )
+                    )
+                ),
+                'expectedNewItem' => array(
+                    'id' => 'https://elsewhere.com/notes/1',
+                )
+            ),
+            array(
+                'id' => 'outboxTest',
+                'eventName' => OutboxActivityEvent::NAME,
+                'event' => new OutboxActivityEvent(
+                    array(
+                        'id' => 'https://example.com/adds/1',
+                        'type' => 'Add',
+                        'object' => array(
+                            'id' => 'https://example.com/notes/1',
+                        ),
+                        'target' => array(
+                            'id' => 'https://example.com/collections/1'
+                        )
+                    ),
+                    TestActivityPubObject::fromArray( array(
+                        'id' => 'https://example.com/actors/1',
+                    ) ),
+                    self::requestWithAttributes(
+                        'https://example.com/actors/1/inbox',
+                        array(
+                            'actor' => TestActivityPubObject::fromArray( array(
+                                'id' => 'https://example.com/actors/1'
+                            ) )
+                        )
+                    )
+                ),
+                'expectedNewItem' => array(
+                    'id' => 'https://example.com/notes/1',
+                )
+            ),
+            array(
+                'id' => 'notAuthorizedTest',
+                'eventName' => OutboxActivityEvent::NAME,
+                'event' => new OutboxActivityEvent(
+                    array(
+                        'id' => 'https://example.com/adds/1',
+                        'type' => 'Add',
+                        'object' => array(
+                            'id' => 'https://example.com/notes/1',
+                        ),
+                        'target' => array(
+                            'id' => 'https://elsewhere.com/collections/1'
+                        )
+                    ),
+                    TestActivityPubObject::fromArray( array(
+                        'id' => 'https://example.com/actors/1',
+                    ) ),
+                    self::requestWithAttributes(
+                        'https://example.com/actors/1/inbox',
+                        array(
+                            'actor' => TestActivityPubObject::fromArray( array(
+                                'id' => 'https://example.com/actors/1'
+                            ) )
+                        )
+                    )
+                ),
+                'expectedException' => AccessDeniedHttpException::class,
+            ),
+        );
+        foreach ( $testCases as $testCase ) {
+            $objectsService = $this->getMock( ObjectsService::class );
+            $objectsService->method( 'dereference')->willReturnCallback( function( $id ) {
+                $objects = self::getObjects();
+                if ( array_key_exists( $id, $objects ) ) {
+                    return TestActivityPubObject::fromArray( $objects[$id] );
+                } else {
+                    return null;
+                }
+            });
+            $collectionsService = $this->getMockBuilder( CollectionsService::class )
+                ->disableOriginalConstructor()
+                ->setMethods( array( 'addItem' ) )
+                ->getMock();
+            if ( array_key_exists( 'expectedNewItem', $testCase ) ) {
+                $collectionsService->expects( $this->once() )
+                    ->method( 'addItem' )
+                    ->with(
+                        $this->anything(),
+                        $this->equalTo( $testCase['expectedNewItem'] )
+                    );
+            } else {
+                $collectionsService->expects( $this->never() )
+                    ->method( 'addItem' );
+            }
+            $addHandler = new AddHandler( $objectsService, $collectionsService );
+            $eventDispatcher = new EventDispatcher();
+            $eventDispatcher->addSubscriber( $addHandler );
+            if ( array_key_exists( 'expectedException', $testCase ) ) {
+                $this->setExpectedException( $testCase['expectedException'] );
+            }
+            $eventDispatcher->dispatch( $testCase['eventName'], $testCase['event'] );
+        }
     }
 }
\ No newline at end of file