diff --git a/modules/user/user.admin.inc b/modules/user/user.admin.inc
index 0596bde..6bdf11b 100644
--- a/modules/user/user.admin.inc
+++ b/modules/user/user.admin.inc
@@ -753,11 +753,14 @@ function theme_user_admin_permissions($variables) {
   $form = $variables['form'];
 
   $roles = user_roles();
+  $modulekey = '';
   foreach (element_children($form['permission']) as $key) {
     $row = array();
+    $class = 'parent';
     // Module name
     if (is_numeric($key)) {
       $row[] = array('data' => drupal_render($form['permission'][$key]), 'class' => array('module'), 'id' => 'module-' . $form['permission'][$key]['#id'], 'colspan' => count($form['role_names']['#value']) + 1);
+      $modulekey = 'module-' . $form['permission'][$key]['#id'];
     }
     else {
       // Permission row.
@@ -765,13 +768,14 @@ function theme_user_admin_permissions($variables) {
         'data' => drupal_render($form['permission'][$key]),
         'class' => array('permission'),
       );
+      $class = 'child';
       foreach (element_children($form['checkboxes']) as $rid) {
         $form['checkboxes'][$rid][$key]['#title'] = $roles[$rid] . ': ' . $form['permission'][$key]['#markup'];
         $form['checkboxes'][$rid][$key]['#title_display'] = 'invisible';
         $row[] = array('data' => drupal_render($form['checkboxes'][$rid][$key]), 'class' => array('checkbox'));
       }
     }
-    $rows[] = $row;
+    $rows[] = array('data' => $row, 'class' => array($modulekey, $class));
   }
   $header[] = (t('Permission'));
   foreach (element_children($form['role_names']) as $rid) {
diff --git a/modules/user/user.css b/modules/user/user.css
index 60f93bf..7ce4fc9 100644
--- a/modules/user/user.css
+++ b/modules/user/user.css
@@ -9,6 +9,14 @@
 #permissions tr.even .form-item {
   white-space: normal;
 }
+html.js #permissions tr.parent td {
+  cursor: pointer;
+  background: url(../../misc/menu-collapsed.png) no-repeat left center;
+}
+html.js #permissions tr.parent td.expanded {
+  background: url(../../misc/menu-expanded.png) no-repeat left center;
+}
+
 #user-admin-settings fieldset .fieldset-description {
   font-size: 0.85em;
   padding-bottom: .5em;
diff --git a/modules/user/user.permissions.js b/modules/user/user.permissions.js
index 4ef576c..fae8fb2 100644
--- a/modules/user/user.permissions.js
+++ b/modules/user/user.permissions.js
@@ -5,7 +5,7 @@
  */
 Drupal.behaviors.permissions = {
   attach: function (context) {
-    $('table#permissions:not(.permissions-processed)').each(function () {
+    $('table#permissions').once('permissions').each(function () {
       // Create dummy checkboxes. We use dummy checkboxes instead of reusing
       // the existing checkboxes here because new checkboxes don't alter the
       // submitted form. If we'd automatically check existing checkboxes, the
@@ -32,7 +32,14 @@ Drupal.behaviors.permissions = {
       $(':checkbox[name^="2["]', this)
         .click(toggle)
         .each(function () { toggle.call(this); });
-    }).addClass('permissions-processed');
+
+      // Provide the collapse/expand functionality.
+      $('tr.parent td', this).addClass('expanded').click(function() {
+        $(this).toggleClass('expanded');
+        var module = $(this).attr('id');
+        $('table#permissions tr.child.' + module).toggle();
+      });
+    });
   }
 };