diff --git a/static/js/activity_page.js b/static/js/activity_page.js
new file mode 100644
index 0000000000..270a670836
--- /dev/null
+++ b/static/js/activity_page.js
@@ -0,0 +1,45 @@
+$(function () {
+    function show_realms_only() {
+        $(".table").each(function () {
+            var table = $(this);
+
+            table.find('tbody tr[data-type="user"]').hide();
+            table.find('tbody tr[data-type="realm"]').show();
+        });
+    }
+
+    function filter_to_realm(realm) {
+        $(".table").each(function () {
+            var table = $(this);
+
+            table.find("tbody tr").hide();
+            var rows = table.find('tbody tr[data-realm="'+realm+'"]');
+            rows.show();
+        });
+
+    }
+
+    function set_up_realm_links() {
+        $("a.realm").on("click", function () {
+            var realm = $(this).attr("data-realm");
+            filter_to_realm(realm);
+        });
+    }
+
+    function set_up_summary_link() {
+        $("a.show-summary").on("click", function () {
+            show_realms_only();
+        });
+    }
+
+    function set_up_show_all_link() {
+        $("a.show-all").on("click", function () {
+            $(".table tbody tr").show();
+        });
+    }
+
+    show_realms_only();
+    set_up_realm_links();
+    set_up_summary_link();
+    set_up_show_all_link();
+});
diff --git a/templates/zerver/activity.html b/templates/zerver/activity.html
index 9e5a4f30ea..124c00bf10 100644
--- a/templates/zerver/activity.html
+++ b/templates/zerver/activity.html
@@ -21,6 +21,10 @@
 {% endfor %}
 </ul>
 
+<a class="show-all">Show all</a>
+&nbsp;
+<a class="show-summary">Show summary</a>
+
 <div class="tab-content">
 
 {% for name, activity in data.iteritems %}
@@ -44,10 +48,14 @@
     </thead>
     <tbody>
     {% for email, row in activity.sorted_rows %}
-        <tr class="{{ row.class }}">
+        <tr class="{{ row.class }}" data-type="{{ row.type }}" data-realm="{{ row.realm }}">
         <td><strong>{{ row.full_name }}</strong></td>
         <td><strong>{{ row.email }}</strong></td>
-        <td><strong>{{ row.realm }}</strong></td>
+        <td>
+            <a class="realm" data-realm="{{ row.realm }}">
+                <strong>{{ row.realm }}</strong>
+            <a>
+        </td>
         <td sorttable_customkey="{{ row.send_message_last|date:'YmdHi' }}">{{ row.send_message_last|date:"M d, H:i" }}</td>
         <td class="number">{{ row.send_message_count }}</td>
         {% if activity.has_pointer %}
diff --git a/zerver/views/__init__.py b/zerver/views/__init__.py
index 331a5ca5f7..ab9cdc10f6 100644
--- a/zerver/views/__init__.py
+++ b/zerver/views/__init__.py
@@ -1786,7 +1786,8 @@ class ActivityTable(object):
                 row = self.rows.setdefault(email,
                                            {'realm': domain,
                                             'full_name': full_name,
-                                            'email': email})
+                                            'email': email,
+                                            'type': 'user'})
                 row[count_field] = count
                 row[last_visit_field] = last_visit
 
@@ -1795,7 +1796,8 @@ class ActivityTable(object):
                 row = self.rows.setdefault(domain,
                                            {'realm': domain,
                                             'full_name': full_name,
-                                            'email': ''})
+                                            'email': '',
+                                            'type': 'realm'})
                 row.setdefault(count_field, 0)
                 row[count_field] += count
 
diff --git a/zproject/settings.py b/zproject/settings.py
index 0cef88731e..261fdecd40 100644
--- a/zproject/settings.py
+++ b/zproject/settings.py
@@ -420,6 +420,7 @@ JS_SPECS = {
     'activity': {
         'source_filenames': (
             'third/sorttable/sorttable.js',
+            'js/activity_page.js',
         ),
         'output_filename': 'min/activity.js'
     },