diff --git a/doctrine-mapping.xsd b/doctrine-mapping.xsd
index 2dde4d9b8..680123fd0 100644
--- a/doctrine-mapping.xsd
+++ b/doctrine-mapping.xsd
@@ -187,8 +187,9 @@
       <xs:element name="sequence-generator" type="orm:sequence-generator" minOccurs="0" maxOccurs="1" />
     </xs:sequence>
     <xs:attribute name="name" type="xs:NMTOKEN" use="required" />
-    <xs:attribute name="type" type="xs:NMTOKEN" use="required" />
+    <xs:attribute name="type" type="xs:NMTOKEN" />
     <xs:attribute name="column" type="xs:NMTOKEN" />
+    <xs:attribute name="association-key" type="xs:boolean" default="false" />
   </xs:complexType>
 
   <xs:complexType name="sequence-generator">
diff --git a/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php b/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php
index 91892e2b3..cd84849ae 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php
@@ -194,7 +194,13 @@ class XmlDriver extends AbstractFileDriver
         }
 
         // Evaluate <id ...> mappings
+        $associationIds = array();
         foreach ($xmlRoot->id as $idElement) {
+            if ((bool)$idElement['association-key'] == true) {
+                $associationIds[(string)$idElement['fieldName']] = true;
+                continue;
+            }
+
             $mapping = array(
                 'id' => true,
                 'fieldName' => (string)$idElement['name'],
@@ -235,6 +241,10 @@ class XmlDriver extends AbstractFileDriver
                     'targetEntity' => (string)$oneToOneElement['target-entity']
                 );
 
+                if (isset($associationIds[$mapping['fieldName']])) {
+                    $mapping['id'] = true;
+                }
+
                 if (isset($oneToOneElement['fetch'])) {
                     $mapping['fetch'] = constant('Doctrine\ORM\Mapping\ClassMetadata::FETCH_' . (string)$oneToOneElement['fetch']);
                 }
@@ -311,6 +321,10 @@ class XmlDriver extends AbstractFileDriver
                     'targetEntity' => (string)$manyToOneElement['target-entity']
                 );
 
+                if (isset($associationIds[$mapping['fieldName']])) {
+                    $mapping['id'] = true;
+                }
+
                 if (isset($manyToOneElement['fetch'])) {
                     $mapping['fetch'] = constant('Doctrine\ORM\Mapping\ClassMetadata::FETCH_' . (string)$manyToOneElement['fetch']);
                 }
diff --git a/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php b/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php
index e714c50a0..0a6c6d0bd 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php
@@ -135,9 +135,15 @@ class YamlDriver extends AbstractFileDriver
             }
         }
 
+        $associationIds = array();
         if (isset($element['id'])) {
             // Evaluate identifier settings
             foreach ($element['id'] as $name => $idElement) {
+                if (isset($idElement['associationKey']) && $idElement['associationKey'] == true) {
+                    $associationIds[$name] = true;
+                    continue;
+                }
+
                 if (!isset($idElement['type'])) {
                     throw MappingException::propertyTypeIsRequired($className, $name);
                 }
@@ -234,6 +240,10 @@ class YamlDriver extends AbstractFileDriver
                     'targetEntity' => $oneToOneElement['targetEntity']
                 );
 
+                if (isset($associationIds[$mapping['fieldName']])) {
+                    $mapping['id'] = true;
+                }
+
                 if (isset($oneToOneElement['fetch'])) {
                     $mapping['fetch'] = constant('Doctrine\ORM\Mapping\ClassMetadata::FETCH_' . $oneToOneElement['fetch']);
                 }
@@ -303,6 +313,10 @@ class YamlDriver extends AbstractFileDriver
                     'targetEntity' => $manyToOneElement['targetEntity']
                 );
 
+                if (isset($associationIds[$mapping['fieldName']])) {
+                    $mapping['id'] = true;
+                }
+
                 if (isset($manyToOneElement['fetch'])) {
                     $mapping['fetch'] = constant('Doctrine\ORM\Mapping\ClassMetadata::FETCH_' . $manyToOneElement['fetch']);
                 }