diff --git a/client.c b/client.c
index fc9f59cb..5a6231ab 100644
--- a/client.c
+++ b/client.c
@@ -1477,6 +1477,7 @@ luaA_client_newindex(lua_State *L)
  * \lfield maximized_horizontal The client is maximized horizontally or not.
  * \lfield maximized_vertical The client is maximized vertically or not.
  * \lfield transient_for Return the client the window is transient for.
+ * \lfield group_id Identification unique to a group of windows.
  * \lfield size_hints A table with size hints of the client: user_position,
  *         user_size, program_position and program_size.
  */
@@ -1600,6 +1601,12 @@ luaA_client_index(lua_State *L)
       case A_TK_FULLSCREEN:
         lua_pushboolean(L, (*c)->isfullscreen);
         break;
+      case A_TK_GROUP_ID:
+        if((*c)->group_win)
+            lua_pushnumber(L, (*c)->group_win);
+        else
+            return 0;
+        break;
       case A_TK_MAXIMIZED_HORIZONTAL:
         lua_pushboolean(L, (*c)->ismaxhoriz);
         break;
diff --git a/common/tokenize.gperf b/common/tokenize.gperf
index c47bbf61..cb7a362a 100644
--- a/common/tokenize.gperf
+++ b/common/tokenize.gperf
@@ -28,6 +28,7 @@ font
 fullscreen
 gap
 geometry
+group_id
 grow
 height
 hide
diff --git a/property.c b/property.c
index a646a395..b641a8b3 100644
--- a/property.c
+++ b/property.c
@@ -192,6 +192,9 @@ property_update_wm_hints(client_t *c, xcb_get_property_reply_t *reply)
 
     if(wmh.flags & XCB_WM_HINT_INPUT)
         c->nofocus = !wmh.input;
+
+    if(wmh.flags & XCB_WM_HINT_WINDOW_GROUP)
+        c->group_win = wmh.window_group;
 }
 
 static int
diff --git a/structs.h b/structs.h
index cb6dbe21..b61d5c7e 100644
--- a/structs.h
+++ b/structs.h
@@ -203,6 +203,8 @@ struct client_t
     window_type_t type;
     /** Window of the client */
     xcb_window_t win;
+    /** Window of the group leader */
+    xcb_window_t group_win;
     /** Client logical screen */
     int screen;
     /** Client physical screen */