diff --git a/lib/Doctrine/ORM/EntityManager.php b/lib/Doctrine/ORM/EntityManager.php
index 04a30dc46..8c0b87e5d 100644
--- a/lib/Doctrine/ORM/EntityManager.php
+++ b/lib/Doctrine/ORM/EntityManager.php
@@ -422,16 +422,11 @@ class EntityManager implements ObjectManager
      * Clears the EntityManager. All entities that are currently managed
      * by this EntityManager become detached.
      *
-     * @param string $entityName
+     * @param string $entityName if given, only entities of this type will get detached
      */
     public function clear($entityName = null)
     {
-        if ($entityName === null) {
-            $this->unitOfWork->clear();
-        } else {
-            //TODO
-            throw new ORMException("EntityManager#clear(\$entityName) not yet implemented.");
-        }
+        $this->unitOfWork->clear($entityName);
     }
 
     /**
diff --git a/lib/Doctrine/ORM/Event/OnClearEventArgs.php b/lib/Doctrine/ORM/Event/OnClearEventArgs.php
index ad89fbc90..60ce4b3eb 100644
--- a/lib/Doctrine/ORM/Event/OnClearEventArgs.php
+++ b/lib/Doctrine/ORM/Event/OnClearEventArgs.php
@@ -36,12 +36,18 @@ class OnClearEventArgs extends \Doctrine\Common\EventArgs
      */
     private $em;
 
+    /**
+     * @var string
+     */
+    private $entityClass;
+
     /**
      * @param \Doctrine\ORM\EntityManager $em
      */
-    public function __construct($em)
+    public function __construct($em, $entityClass = null)
     {
         $this->em = $em;
+        $this->entityClass = $entityClass;
     }
 
     /**
@@ -51,4 +57,24 @@ class OnClearEventArgs extends \Doctrine\Common\EventArgs
     {
         return $this->em;
     }
+
+    /**
+     * Name of the entity class that is cleared, or empty if all are cleared.
+     *
+     * @return string
+     */
+    public function getEntityClass()
+    {
+        return $this->entityClass;
+    }
+
+    /**
+     * Check if event clears all entities.
+     *
+     * @return bool
+     */
+    public function clearsAllEntities()
+    {
+        return $this->entityClass === null;
+    }
 }
\ No newline at end of file
diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index 6851d25e4..8f5977e5d 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -1567,8 +1567,9 @@ class UnitOfWork implements PropertyChangedListener
      * 
      * @param object $entity
      * @param array $visited
+     * @param boolean $noCascade if true, don't cascade detach operation
      */
-    private function doDetach($entity, array &$visited)
+    private function doDetach($entity, array &$visited, $noCascade = false)
     {
         $oid = spl_object_hash($entity);
         if (isset($visited[$oid])) {
@@ -1590,8 +1591,10 @@ class UnitOfWork implements PropertyChangedListener
             case self::STATE_DETACHED:
                 return;
         }
-        
-        $this->cascadeDetach($entity, $visited);
+
+        if (!$noCascade) {
+            $this->cascadeDetach($entity, $visited);
+        }
     }
     
     /**
@@ -1842,28 +1845,41 @@ class UnitOfWork implements PropertyChangedListener
 
     /**
      * Clears the UnitOfWork.
+     *
+     * @param string $entityName if given, only entities of this type will get detached
      */
-    public function clear()
+    public function clear($entityName = null)
     {
-        $this->identityMap =
-        $this->entityIdentifiers =
-        $this->originalEntityData =
-        $this->entityChangeSets =
-        $this->entityStates =
-        $this->scheduledForDirtyCheck =
-        $this->entityInsertions =
-        $this->entityUpdates =
-        $this->entityDeletions =
-        $this->collectionDeletions =
-        $this->collectionUpdates =
-        $this->extraUpdates =
-        $this->orphanRemovals = array();
-        if ($this->commitOrderCalculator !== null) {
-            $this->commitOrderCalculator->clear();
+        if ($entityName === null) {
+            $this->identityMap =
+            $this->entityIdentifiers =
+            $this->originalEntityData =
+            $this->entityChangeSets =
+            $this->entityStates =
+            $this->scheduledForDirtyCheck =
+            $this->entityInsertions =
+            $this->entityUpdates =
+            $this->entityDeletions =
+            $this->collectionDeletions =
+            $this->collectionUpdates =
+            $this->extraUpdates =
+            $this->orphanRemovals = array();
+            if ($this->commitOrderCalculator !== null) {
+                $this->commitOrderCalculator->clear();
+            }
+        } else {
+            $visited = array();
+            foreach ($this->identityMap as $className => $entities) {
+                if ($className === $entityName) {
+                    foreach ($entities as $entity) {
+                        $this->doDetach($entity, $visited, true);
+                    }
+                }
+            }
         }
 
         if ($this->evm->hasListeners(Events::onClear)) {
-            $this->evm->dispatchEvent(Events::onClear, new Event\OnClearEventArgs($this->em));
+            $this->evm->dispatchEvent(Events::onClear, new Event\OnClearEventArgs($this->em, $entityName));
         }
     }
     
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsUser.php b/tests/Doctrine/Tests/Models/CMS/CmsUser.php
index f02d0441b..0c7b007d1 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsUser.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsUser.php
@@ -35,7 +35,7 @@ class CmsUser
      */
     public $phonenumbers;
     /**
-     * @OneToMany(targetEntity="CmsArticle", mappedBy="user")
+     * @OneToMany(targetEntity="CmsArticle", mappedBy="user", cascade={"detach"})
      */
     public $articles;
     /**
@@ -48,7 +48,7 @@ class CmsUser
      */
     public $email;
     /**
-     * @ManyToMany(targetEntity="CmsGroup", inversedBy="users", cascade={"persist", "merge"})
+     * @ManyToMany(targetEntity="CmsGroup", inversedBy="users", cascade={"persist", "merge", "detach"})
      * @JoinTable(name="cms_users_groups",
      *      joinColumns={@JoinColumn(name="user_id", referencedColumnName="id")},
      *      inverseJoinColumns={@JoinColumn(name="group_id", referencedColumnName="id")}
diff --git a/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php b/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php
index 8d636dffb..a2e2d05dd 100644
--- a/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php
+++ b/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php
@@ -980,4 +980,54 @@ class BasicFunctionalTest extends \Doctrine\Tests\OrmFunctionalTestCase
         $this->assertTrue($article->user->__isInitialized__, "...but its initialized!");
         $this->assertEquals($qc+2, $this->getCurrentQueryCount());
     }
+
+    /**
+     * @group DDC-1278
+     */
+    public function testClearWithEntityName()
+    {
+        $user = new CmsUser;
+        $user->name = 'Dominik';
+        $user->username = 'domnikl';
+        $user->status = 'developer';
+
+        $address = new CmsAddress();
+        $address->city = "Springfield";
+        $address->zip = "12354";
+        $address->country = "Germany";
+        $address->street = "Foo Street";
+        $address->user = $user;
+        $user->address = $address;
+
+        $article1 = new CmsArticle();
+        $article1->topic = 'Foo';
+        $article1->text = 'Foo Text';
+
+        $article2 = new CmsArticle();
+        $article2->topic = 'Bar';
+        $article2->text = 'Bar Text';
+
+        $user->addArticle($article1);
+        $user->addArticle($article2);
+
+        $this->_em->persist($article1);
+        $this->_em->persist($article2);
+        $this->_em->persist($address);
+        $this->_em->persist($user);
+        $this->_em->flush();
+
+        $unitOfWork = $this->_em->getUnitOfWork();
+
+        $this->_em->clear('Doctrine\Tests\Models\CMS\CmsUser');
+
+        $this->assertEquals(\Doctrine\ORM\UnitOfWork::STATE_DETACHED, $unitOfWork->getEntityState($user));
+
+        $this->assertEquals(\Doctrine\ORM\UnitOfWork::STATE_MANAGED, $unitOfWork->getEntityState($address));
+        $this->assertEquals(\Doctrine\ORM\UnitOfWork::STATE_MANAGED, $unitOfWork->getEntityState($article1));
+        $this->assertEquals(\Doctrine\ORM\UnitOfWork::STATE_MANAGED, $unitOfWork->getEntityState($article2));
+
+        $this->_em->clear();
+
+        $this->assertEquals(\Doctrine\ORM\UnitOfWork::STATE_DETACHED, $unitOfWork->getEntityState($address));
+    }
 }