diff --git a/lib/Gitlab/Api/Groups.php b/lib/Gitlab/Api/Groups.php
index 38039b787..b771dc579 100644
--- a/lib/Gitlab/Api/Groups.php
+++ b/lib/Gitlab/Api/Groups.php
@@ -91,15 +91,16 @@ public function transfer($group_id, $project_id)
 
     /**
      * @param integer $id
+     * @param integer|null $user_id
      * @param array $parameters
      * @return mixed
      */
-    public function allMembers($id, array $parameters = [])
+    public function allMembers($id, $user_id = null, array $parameters = [])
     {
         $resolver = $this->createOptionsResolver();
         $resolver->setDefined('query');
 
-        return $this->get('groups/'.$this->encodePath($id).'/members/all', $resolver->resolve($parameters));
+        return $this->get('groups/'.$this->encodePath($id).'/members/all/'.$this->encodePath($user_id), $resolver->resolve($parameters));
     }
 
     /**
diff --git a/lib/Gitlab/Api/Projects.php b/lib/Gitlab/Api/Projects.php
index e5ea9b6cc..2569162e1 100644
--- a/lib/Gitlab/Api/Projects.php
+++ b/lib/Gitlab/Api/Projects.php
@@ -286,18 +286,19 @@ public function deletePipeline($project_id, $pipeline_id)
     {
         return $this->delete($this->getProjectPath($project_id, 'pipelines/'.$this->encodePath($pipeline_id)));
     }
-    
+
     /**
      * @param integer $project_id
+     * @param integer|null $user_id
      * @param array $parameters
      * @return mixed
      */
-    public function allMembers($project_id, $parameters = [])
+    public function allMembers($project_id, $user_id = null, $parameters = [])
     {
         $resolver = $this->createOptionsResolver();
         $resolver->setDefined('query');
 
-        return $this->get('projects/'.$this->encodePath($project_id).'/members/all', $resolver->resolve($parameters));
+        return $this->get('projects/'.$this->encodePath($project_id).'/members/all/'.$this->encodePath($user_id), $resolver->resolve($parameters));
     }
 
     /**
diff --git a/lib/Gitlab/Model/Group.php b/lib/Gitlab/Model/Group.php
index 97628f3d2..89f867ce4 100644
--- a/lib/Gitlab/Model/Group.php
+++ b/lib/Gitlab/Model/Group.php
@@ -116,6 +116,30 @@ public function transfer($project_id)
         return Group::fromArray($this->getClient(), $data);
     }
 
+    /**
+     * @param integer|null $user_id
+     * @param bool $all
+     * @return array|User
+     */
+    public function allMembers($user_id = null, $all = false)
+    {
+        if ($all) {
+            $data = (new \Gitlab\ResultPager($this->client))->fetchAll($this->client->groups(), "allMembers", [$this->id, $user_id]);
+        } else {
+            $data = $this->client->groups()->allMembers($this->id, $user_id);
+        }
+
+        if ($user_id != null) {
+            return User::fromArray($this->getClient(), $data);
+        } else {
+            $members = array();
+            foreach ($data as $member) {
+                $members[] = User::fromArray($this->getClient(), $member);
+            }
+            return $members;
+        }
+    }
+
     /**
      * @return User[]
      */
diff --git a/lib/Gitlab/Model/Project.php b/lib/Gitlab/Model/Project.php
index 8d08c1165..471bdfa15 100644
--- a/lib/Gitlab/Model/Project.php
+++ b/lib/Gitlab/Model/Project.php
@@ -217,6 +217,30 @@ public function remove()
         return true;
     }
 
+    /**
+     * @param integer|null $user_id
+     * @param bool $all
+     * @return array|User
+     */
+    public function allMembers($user_id = null, $all = false)
+    {
+        if ($all) {
+            $data = (new \Gitlab\ResultPager($this->client))->fetchAll($this->client->projects(), "allMembers", [$this->id, $user_id]);
+        } else {
+            $data = $this->client->projects()->allMembers($this->id, $user_id);
+        }
+
+        if ($user_id != null) {
+            return User::fromArray($this->getClient(), $data);
+        } else {
+            $members = array();
+            foreach ($data as $member) {
+                $members[] = User::fromArray($this->getClient(), $member);
+            }
+            return $members;
+        }
+    }
+
     /**
      * @param string $username_query
      * @return User[]
diff --git a/test/Gitlab/Tests/Api/GroupsTest.php b/test/Gitlab/Tests/Api/GroupsTest.php
index b4da1de4d..571cf3193 100644
--- a/test/Gitlab/Tests/Api/GroupsTest.php
+++ b/test/Gitlab/Tests/Api/GroupsTest.php
@@ -199,13 +199,29 @@ public function shouldGetAllMembers()
         $api = $this->getApiMock();
         $api->expects($this->once())
             ->method('get')
-            ->with('groups/1/members/all')
+            ->with('groups/1/members/all/')
             ->will($this->returnValue($expectedArray))
         ;
 
         $this->assertEquals($expectedArray, $api->allMembers(1));
     }
 
+    /**
+     * @test
+     */
+    public function shouldGetAllMembersUserID()
+    {
+        $expectedArray = array('id' => 2, 'name' => 'Bob');
+
+        $api = $this->getApiMock();
+        $api->expects($this->once())
+            ->method('get')
+            ->with('groups/1/members/all/2')
+            ->will($this->returnValue($expectedArray));
+
+        $this->assertEquals($expectedArray, $api->allMembers(1, 2));
+    }
+
     /**
      * @test
      */
diff --git a/test/Gitlab/Tests/Api/ProjectsTest.php b/test/Gitlab/Tests/Api/ProjectsTest.php
index 043c4216b..9d85b61a4 100644
--- a/test/Gitlab/Tests/Api/ProjectsTest.php
+++ b/test/Gitlab/Tests/Api/ProjectsTest.php
@@ -661,12 +661,28 @@ public function shouldGetAllMembers()
         $api = $this->getApiMock();
         $api->expects($this->once())
             ->method('get')
-            ->with('projects/1/members/all')
+            ->with('projects/1/members/all/')
             ->will($this->returnValue($expectedArray));
 
         $this->assertEquals($expectedArray, $api->allMembers(1));
     }
 
+    /**
+     * @test
+     */
+    public function shouldGetAllMembersUserID()
+    {
+        $expectedArray = array('id' => 2, 'name' => 'Bob');
+
+        $api = $this->getApiMock();
+        $api->expects($this->once())
+            ->method('get')
+            ->with('projects/1/members/all/2')
+            ->will($this->returnValue($expectedArray));
+
+        $this->assertEquals($expectedArray, $api->allMembers(1, 2));
+    }
+
     /**
      * @test
      */