diff --git a/og.info b/og.info
index 28f131c..04f4b71 100644
--- a/og.info
+++ b/og.info
@@ -16,7 +16,7 @@ files[] = includes/og.membership.inc
 files[] = includes/og.membership_type.inc
 files[] = includes/views/og.views.inc
 
-; Test files.
+; Test files
 files[] = og.test
 files[] = tests/upgrade/og.upgrade.test
 
diff --git a/og.module b/og.module
index cc69685..efa5e55 100644
--- a/og.module
+++ b/og.module
@@ -1583,6 +1583,140 @@ function og_get_membership($group_type, $gid, $entity_type, $etid) {
   return FALSE;
 }
 
+/**
+ * Implements hook_entity_query_alter().
+ *
+ * Add "og_membership" tag if there's a group audience field in the query.
+ *
+ * @see og_query_og_membership_alter().
+ */
+function og_entity_query_alter(EntityFieldQuery $query) {
+  foreach ($query->fieldConditions as $values) {
+    if (og_is_group_audience_field($values['field']['field_name'])) {
+      $query->addTag('og_membership');
+      return;
+    }
+  }
+}
+
+/**
+ * Implements hook_query_QUERY_TAG_alter().
+ *
+ * Join the {og_membership} table and alter the query.
+ */
+function og_query_og_membership_alter(QueryAlterableInterface $query) {
+  $tables = &$query->getTables();
+  $fields = &$query->getFields();
+  $conditions =  &$query->conditions();
+
+  // Find the group-audience fields.
+  $field_names = array();
+  foreach ($query->alterMetaData['entity_field_query']->fieldConditions as $values) {
+    $field_name = $values['field']['field_name'];
+    if (og_is_group_audience_field($field_name)) {
+      $field_names[] = $field_name;
+    }
+  }
+
+  $aliases = array();
+  $base_table = FALSE;
+  $base_table_alias = '';
+
+  foreach ($tables as $alias => $values) {
+    if (!$base_table_alias && empty($values['join type'])) {
+      $base_table_alias = $alias;
+    }
+
+    if (strpos($alias, 'field_data') !== 0) {
+      continue;
+    }
+    $field_name = substr($values['table'], 11);
+    if (!in_array($field_name, $field_names)) {
+      continue;
+    }
+
+    if (empty($values['join type'])) {
+      // This is the base table, so remove it in favor of OG membership.
+      $base_table = TRUE;
+    }
+
+    unset($tables[$alias]);
+    $aliases[$alias] = $field_name;
+  }
+
+  foreach ($aliases as $alias => $field_name) {
+    foreach ($tables as $key => $values) {
+      $condition = str_replace("$alias.entity_type", 'ogm.entity_type', $values['condition']);
+      $condition = str_replace("$alias.entity_id", 'ogm.etid', $condition);
+      $tables[$key]['condition'] = $condition;
+    }
+  }
+
+  if ($base_table) {
+    // Point the revision ID and bundle to the base entity.
+    $entity_type = $query->alterMetaData['entity_field_query']->entityConditions['entity_type']['value'];
+    $entity_type = is_array($entity_type) ? $entity_type[0] : $entity_type;
+    $entity_info = entity_get_info($entity_type);
+
+    // If the table of the base entity does not exist (e.g. there is no
+    // property condition), we need to add it, as we don't have the
+    // revision ID and bundle in {og_membership} table.
+    if (strpos($base_table_alias, 'field_data') === 0) {
+      $id = $entity_info['entity keys']['id'];
+      $query->innerJoin($entity_type, $entity_type, "$entity_type.$id = ogm.etid");
+    }
+
+    $fields['revision_id']['table'] = $entity_type;
+    $fields['revision_id']['field'] = $entity_info['entity keys']['revision'];
+
+    $fields['bundle']['table'] = $entity_type;
+    $fields['bundle']['field'] = $entity_info['entity keys']['bundle'];
+
+    $fields['entity_type']['table'] = 'ogm';
+    $fields['entity_id']['table'] = 'ogm';
+    $fields['entity_id']['field'] = 'etid';
+
+    $ogm = array(
+      'join type' => NULL,
+      'table' => 'og_membership',
+      'alias' => 'ogm',
+      'condition' => '',
+      'arguments' => array(),
+    );
+
+    $tables = array_merge(array('ogm' => $ogm), $tables);
+  }
+  else {
+    $query->join('og_membership', 'ogm', "ogm.etid = $base_table_alias.entity_id");
+  }
+
+  foreach ($conditions as $delta => $values) {
+    if (!is_array($values)) {
+      continue;
+    }
+    if (strpos($values['field'], 'field_data_') !== 0) {
+      continue;
+    }
+
+    $args = explode('.', $values['field']);
+
+    if (empty($aliases[$args[0]])) {
+      continue;
+    }
+    $field_name = $aliases[$args[0]];
+
+    if ($args[1] == 'deleted') {
+      unset($conditions[$delta]);
+    }
+    elseif (strpos($args[1], 'target_id')) {
+      $conditions[$delta]['field'] = 'ogm.gid';
+    }
+    else {
+      $conditions[$delta]['field'] = 'ogm.' . $args[1];
+    }
+  }
+}
+
 
 /**
  * Inserts or updates an OG membership entity into the database.
@@ -1792,7 +1926,7 @@ function og_check_field_cardinality($entity_type, $entity, $field_name) {
   @param $group_type
  *   The entity type of the group.
  * @param $gid
- *   The group ID.
+ *   The group entity or ID.
  * @param $values
  *   Array with the information to pass along, until it is processed in the
  *   field handlers.
@@ -1834,8 +1968,16 @@ function og_group($group_type, $gid, $values = array()) {
   $bundle = $wrapper->getBundle();
   $id = $wrapper->getIdentifier();
 
-  $group = entity_load_single($group_type, $gid);
-  list(,, $group_bundle) = entity_extract_ids($group_type, $group);
+  if (is_object($gid)) {
+    $group = $gid;
+
+  }
+  else {
+    $group = entity_load_single($group_type, $gid);
+  }
+
+  // the group ID might be the entity, so re-popualte it.
+  list($gid,, $group_bundle) = entity_extract_ids($group_type, $group);
 
   // Get membership if exists.
   $og_membership = og_get_membership($group_type, $gid, $entity_type, $id);
diff --git a/og.test b/og.test
index 099e3fa..401eee8 100644
--- a/og.test
+++ b/og.test
@@ -1046,3 +1046,191 @@ class OgRoleRevoke extends DrupalWebTestCase {
   }
 }
 
+/**
+ * Test queying group-audience fields using entityFieldQuery.
+ */
+class OgEntityFieldQueryTestCase extends DrupalWebTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'OG audience fields query',
+      'description' => 'Test queying group-audience fields using entityFieldQuery.',
+      'group' => 'Organic groups',
+    );
+  }
+
+  function setUp() {
+    parent::setUp('og', 'entity_feature');
+
+    $user1 = $this->drupalCreateUser();
+    $type = $this->drupalCreateContentType();
+    $group_type = $type->type;
+
+    $type = $this->drupalCreateContentType();
+    $group_content_type = $type->type;
+
+    og_create_field(OG_GROUP_FIELD, 'node', $group_type);
+    og_create_field(OG_GROUP_FIELD, 'entity_test', 'main');
+
+    // Add audience field to reference node.
+    $og_field = og_fields_info(OG_AUDIENCE_FIELD);
+    og_create_field('og_node', 'node', $group_content_type, $og_field);
+
+    // Add audience field to reference entity-test, and user.
+    $og_field['field']['settings']['target_type'] = 'entity_test';
+    og_create_field('og_entity_test', 'node', $group_content_type, $og_field);
+    og_create_field('og_entity_test', 'user', 'user', $og_field);
+
+    // Create a non-group audience, entity-refence field.
+    $field = array(
+      'entity_types' => array('node'),
+      'settings' => array(
+        'handler' => 'base',
+        'target_type' => 'node',
+        'handler_settings' => array(
+          'target_bundles' => array(),
+        ),
+      ),
+      'field_name' => 'node_reference',
+      'type' => 'entityreference',
+      'cardinality' => 1,
+    );
+    $field = field_create_field($field);
+    $instance = array(
+      'field_name' => 'node_reference',
+      'bundle' => $group_content_type,
+      'entity_type' => 'node',
+    );
+    field_create_instance($instance);
+
+    // Create two groups.
+    $group1 = entity_create('entity_test', array('name' => 'main', 'uid' => $user1->uid));
+    $wrapper = entity_metadata_wrapper('entity_test', $group1);
+    $wrapper->{OG_GROUP_FIELD}->set(1);
+    $wrapper->save();
+
+    $settings = array(
+      'type' => $group_type,
+      'uid' => $user1->uid,
+    );
+    $settings[OG_GROUP_FIELD][LANGUAGE_NONE][0]['value'] = 1;
+    $group2 = $this->drupalCreateNode($settings);
+
+    $settings = array(
+      'type' => $group_content_type,
+      'uid' => $user1->uid,
+    );
+    $node = $this->drupalCreateNode($settings);
+
+    $wrapper = entity_metadata_wrapper('node', $node);
+    $wrapper->node_reference->set($group2);
+    $wrapper->save();
+
+    $values = array(
+      'entity_type' => 'node',
+      'entity' => $node,
+    );
+
+    og_group('entity_test', $group1, $values);
+    og_group('node', $group2, $values);
+
+    $this->group1 = $group1;
+    $this->group2 = $group2;
+    $this->node = $node;
+    $this->user1 = $user1;
+  }
+
+  /**
+   * Test the following query scenarios:
+   *
+   * - Single group audience.
+   * - Multiple group audience.
+   * - Single group audience first, with another non-audience field.
+   * - Non-audience field first, with single group audience.
+   * - Multiple entity types in entityCondition().
+   * - No entity property.
+   * - Count query.
+   */
+  function testEntityFieldQuery()  {
+    $group1 = $this->group1;
+    $group2 = $this->group2;
+    $node = $this->node;
+    $user1 = $this->user1;
+
+    // Single group audience.
+    $query = new EntityFieldQuery();
+    $result = $query
+      ->entityCondition('entity_type', 'node')
+      ->propertyCondition('type', $node->type)
+      ->fieldCondition('og_node', 'target_id', $group2->nid)
+      ->execute();
+
+    $this->assertEqual(array_keys($result['node']), array($node->nid), 'Single group audience query is correct.');
+
+    // Multiple group audience.
+    $query = new EntityFieldQuery();
+    $result = $query
+      ->entityCondition('entity_type', 'node')
+      ->propertyCondition('type', $node->type)
+      ->fieldCondition('og_node', 'target_id', $group2->nid)
+      ->fieldCondition('og_entity_test', 'target_id', $group1->pid)
+      ->execute();
+
+    $this->assertEqual(array_keys($result['node']), array($node->nid), 'Multiple group audience query is correct.');
+
+    // Single group audience first, with another non-audience field.
+    $query = new EntityFieldQuery();
+    $result = $query
+      ->entityCondition('entity_type', 'node')
+      ->propertyCondition('type', $node->type)
+      ->fieldCondition('og_node', 'target_id', $group2->nid)
+      ->fieldCondition('node_reference', 'target_id', $group2->nid)
+      ->execute();
+
+    $this->assertEqual(array_keys($result['node']), array($node->nid), 'Single group audience first, with another non-audience field query is correct.');
+
+    // Non-audience field first, with single group audience.
+    $query = new EntityFieldQuery();
+    $result = $query
+      ->entityCondition('entity_type', 'node')
+      ->propertyCondition('type', $node->type)
+      ->fieldCondition('node_reference', 'target_id', $group2->nid)
+      ->fieldCondition('og_node', 'target_id', $group2->nid)
+      ->execute();
+
+    $this->assertEqual(array_keys($result['node']), array($node->nid), 'Non-audience field first, with single group audience query is correct.');
+
+    // Multiple entity types in entityCondition().
+    $query = new EntityFieldQuery();
+    $result = $query
+      ->entityCondition('entity_type', array('node', 'user'), 'IN')
+      ->fieldCondition('node_reference', 'target_id', $group2->nid)
+      ->fieldCondition('og_node', 'target_id', $group2->nid)
+      ->execute();
+
+    $this->assertEqual(array_keys($result['node']), array($node->nid), 'Multiple entity types in entityCondition() query is correct.');
+
+    // No entity property.
+    $query = new EntityFieldQuery();
+    $result = $query
+      ->entityCondition('entity_type', array('node', 'user'), 'IN')
+      ->fieldCondition('og_node', 'target_id', $group2->nid)
+      ->execute();
+
+    $this->assertTrue(array_keys($result['node']) == array($node->nid) && array_keys($result['user']) == array($user1->uid), 'Multiple entity types in entityCondition() query is correct.');
+
+    // Count query.
+    $query = new EntityFieldQuery();
+    $result = $query
+      ->entityCondition('entity_type', 'node')
+      ->propertyCondition('type', $node->type)
+      ->fieldCondition('og_node', 'target_id', $group2->nid)
+      ->count()
+      ->execute();
+
+    $this->assertEqual($result, 1, 'Count query is correct.');
+  }
+}
+
+
+