diff --git a/lib/Doctrine/Common/Collections/ArrayCollection.php b/lib/Doctrine/Common/Collections/ArrayCollection.php
index 58ebab175..a1af5d948 100644
--- a/lib/Doctrine/Common/Collections/ArrayCollection.php
+++ b/lib/Doctrine/Common/Collections/ArrayCollection.php
@@ -247,7 +247,7 @@ class ArrayCollection implements Collection
      * @param mixed $element The element to search for.
      * @return mixed The key/index of the element or FALSE if the element was not found.
      */
-    public function search($element)
+    public function indexOf($element)
     {
         return array_search($element, $this->_elements, true);
     }
diff --git a/lib/Doctrine/Common/Collections/Collection.php b/lib/Doctrine/Common/Collections/Collection.php
index c97daa09c..6b415baaf 100644
--- a/lib/Doctrine/Common/Collections/Collection.php
+++ b/lib/Doctrine/Common/Collections/Collection.php
@@ -21,20 +21,21 @@
 
 namespace Doctrine\Common\Collections;
 
+use Closure, Countable, IteratorAggregate, ArrayAccess;
+
 /**
  * The missing (SPL) Collection/Array/OrderedMap interface.
  * 
  * A Collection resembles the nature of a regular PHP array. That is,
- * it is essentially an ordered map that can syntactically also be used
+ * it is essentially an <b>ordered map</b> that can also be used
  * like a list.
  * 
- * A Collection has an internal iterator just like a PHP array. In addition
+ * A Collection has an internal iterator just like a PHP array. In addition,
  * a Collection can be iterated with external iterators, which is preferrable.
  * To use an external iterator simply use the foreach language construct to
- * iterate over the collection (which calls getIterator() internally) or
- * explicitly retrieve an iterator though getIterator() which can then be
+ * iterate over the collection (which calls {@link getIterator()} internally) or
+ * explicitly retrieve an iterator though {@link getIterator()} which can then be
  * used to iterate over the collection.
- * 
  * You can not rely on the internal iterator of the collection being at a certain
  * position unless you explicitly positioned it before. Prefer iteration with
  * external iterators.
@@ -47,10 +48,10 @@ namespace Doctrine\Common\Collections;
  * @author  Jonathan Wage <jonwage@gmail.com>
  * @author  Roman Borschel <roman@code-factory.org>
  */
-interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
+interface Collection extends Countable, IteratorAggregate, ArrayAccess
 {
     /**
-     * Adds an element to the collection.
+     * Adds an element at the end of the collection.
      *
      * @param mixed $element The element to add.
      * @return boolean Always TRUE.
@@ -61,31 +62,31 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      * Clears the collection, removing all elements.
      */
     function clear();
-    
+
     /**
      * Checks whether an element is contained in the collection.
-     * This is an O(n) operation.
+     * This is an O(n) operation, where n is the size of the collection.
      *
-     * @param mixed $element The element to check for.
+     * @param mixed $element The element to search for.
      * @return boolean TRUE if the collection contains the element, FALSE otherwise.
      */
     function contains($element);
-    
+
     /**
-     * Checks whether the collection is empty.
+     * Checks whether the collection is empty (contains no elements).
      *
      * @return boolean TRUE if the collection is empty, FALSE otherwise.
      */
     function isEmpty();
-    
+
     /**
-     * Removes the element with the specified key/index from the collection.
+     * Removes the element at the specified index from the collection.
      * 
-     * @param string|integer $key The key/index of the element to remove.
+     * @param string|integer $key The kex/index of the element to remove.
      * @return mixed The removed element or NULL, if the collection did not contain the element.
      */
     function remove($key);
-    
+
     /**
      * Removes an element from the collection.
      *
@@ -93,7 +94,7 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      * @return mixed The removed element or NULL, if the collection did not contain the element.
      */
     function removeElement($element);
-    
+
     /**
      * Checks whether the collection contains an element with the specified key/index.
      * 
@@ -102,15 +103,15 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      *          FALSE otherwise.
      */
     function containsKey($key);
-    
+
     /**
-     * Gets an element with a specified key / at a specified index.
+     * Gets the element at the specified key/index.
      * 
      * @param string|integer $key The key/index of the element to retrieve.
      * @return mixed
      */
     function get($key);
-    
+
     /**
      * Gets all keys/indices of the collection.
      *
@@ -118,7 +119,7 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      *          elements in the collection.
      */
     function getKeys();
-    
+
     /**
      * Gets all values of the collection. 
      * 
@@ -126,7 +127,7 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      *          appear in the collection.
      */
     function getValues();
-    
+
     /**
      * Sets an element in the collection at the specified key/index.
      * 
@@ -134,14 +135,14 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      * @param mixed $value The element to set.
      */
     function set($key, $value);
-    
+
     /**
-     * Gets a plain PHP array representation of the collection.
+     * Gets a native PHP array representation of the collection.
      * 
      * @return array
      */
     function toArray();
-    
+
     /**
      * Sets the internal iterator to the first element in the collection and
      * returns this element.
@@ -149,7 +150,7 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      * @return mixed
      */
     function first();
-    
+
     /**
      * Sets the internal iterator to the last element in the collection and
      * returns this element.
@@ -157,22 +158,78 @@ interface Collection extends \Countable, \IteratorAggregate, \ArrayAccess
      * @return mixed
      */
     function last();
-    
+
     /**
      * Gets the key/index of the element at the current iterator position.
      *
      */
     function key();
-    
+
     /**
      * Gets the element of the collection at the current iterator position.
      *
      */
     function current();
-    
+
     /**
      * Moves the internal iterator position to the next element.
      *
      */
     function next();
+
+    /**
+     * Tests for the existence of an element that satisfies the given predicate.
+     *
+     * @param Closure $p The predicate.
+     * @return boolean TRUE if the predicate is TRUE for at least one element, FALSE otherwise.
+     */
+    function exists(Closure $p);
+
+    /**
+     * Returns all the elements of this collection that satisfy the predicate p.
+     * The order of the elements is preserved.
+     *
+     * @param Closure $p The predicate used for filtering.
+     * @return Collection A collection with the results of the filter operation.
+     */
+    function filter(Closure $p);
+
+    /**
+     * Applies the given predicate p to all elements of this collection,
+     * returning true, if the predicate yields true for all elements.
+     *
+     * @param Closure $p The predicate.
+     * @return boolean TRUE, if the predicate yields TRUE for all elements, FALSE otherwise.
+     */
+    function forAll(Closure $p);
+
+    /**
+     * Applies the given function to each element in the collection and returns
+     * a new collection with the elements returned by the function.
+     *
+     * @param Closure $func
+     * @return Collection
+     */
+    function map(Closure $func);
+
+    /**
+     * Partitions this collection in two collections according to a predicate.
+     * Keys are preserved in the resulting collections.
+     *
+     * @param Closure $p The predicate on which to partition.
+     * @return array An array with two elements. The first element contains the collection
+     *               of elements where the predicate returned TRUE, the second element
+     *               contains the collection of elements where the predicate returned FALSE.
+     */
+    function partition(Closure $p);
+
+    /**
+     * Gets the index/key of a given element. The comparison of two elements is strict,
+     * that means not only the value but also the type must match.
+     * For objects this means reference equality.
+     *
+     * @param mixed $element The element to search for.
+     * @return mixed The key/index of the element or FALSE if the element was not found.
+     */
+    function indexOf($element);
 }
\ No newline at end of file
diff --git a/lib/Doctrine/ORM/PersistentCollection.php b/lib/Doctrine/ORM/PersistentCollection.php
index 886d3b0b4..d19537c27 100644
--- a/lib/Doctrine/ORM/PersistentCollection.php
+++ b/lib/Doctrine/ORM/PersistentCollection.php
@@ -22,7 +22,8 @@
 namespace Doctrine\ORM;
 
 use Doctrine\ORM\Mapping\AssociationMapping,
-    \Closure;
+    Doctrine\Common\Collections\Collection,
+    Closure;
 
 /**
  * A PersistentCollection represents a collection of elements that have persistent state.
@@ -40,7 +41,7 @@ use Doctrine\ORM\Mapping\AssociationMapping,
  * @author    Roman Borschel <roman@code-factory.org>
  * @author    Giorgio Sironi <piccoloprincipeazzurro@gmail.com>
  */
-final class PersistentCollection implements \Doctrine\Common\Collections\Collection
+final class PersistentCollection implements Collection
 {
     /**
      * A snapshot of the collection at the moment it was fetched from the database.
@@ -443,10 +444,10 @@ final class PersistentCollection implements \Doctrine\Common\Collections\Collect
     /**
      * {@inheritdoc}
      */
-    public function search($element)
+    public function indexOf($element)
     {
         $this->_initialize();
-        return $this->_coll->search($element);
+        return $this->_coll->indexOf($element);
     }
 
     /**
diff --git a/tests/Doctrine/Tests/Common/Collections/CollectionTest.php b/tests/Doctrine/Tests/Common/Collections/CollectionTest.php
index 4e642905f..83bb842f5 100644
--- a/tests/Doctrine/Tests/Common/Collections/CollectionTest.php
+++ b/tests/Doctrine/Tests/Common/Collections/CollectionTest.php
@@ -98,7 +98,7 @@ class CollectionTest extends \Doctrine\Tests\DoctrineTestCase
     public function testSearch()
     {
         $this->_coll[0] = 'test';
-        $this->assertEquals(0, $this->_coll->search('test'));
+        $this->assertEquals(0, $this->_coll->indexOf('test'));
     }
 
     public function testGet()