diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.html b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
index 3f5493c5a3..f7290969e2 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.html
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
@@ -124,7 +124,7 @@ limitations under the License.
         padding: .5em 0 1em;
       }
     </style>
-    <div class$="[[_computeClass(expanded, showAvatar)]]">
+    <div class$="[[_computeClass(_expanded, showAvatar)]]">
       <gr-avatar account="[[author]]" image-size="100"></gr-avatar>
       <div class="contentContainer">
         <div class="name" on-tap="_handleNameTap">[[author.name]]</div>
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.js b/polygerrit-ui/app/elements/change/gr-message/gr-message.js
index 02caa0d935..cebaf5c432 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.js
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.js
@@ -45,11 +45,6 @@
         observer: '_commentsChanged',
       },
       config: Object,
-      expanded: {
-        type: Boolean,
-        value: true,
-        reflectToAttribute: true,
-      },
       hideAutomated: {
         type: Boolean,
         value: false,
@@ -72,6 +67,11 @@
         computed: '_computeShowReplyButton(message, _loggedIn)',
       },
       projectConfig: Object,
+      // Computed property needed to trigger Polymer value observing.
+      _expanded: {
+        type: Object,
+        computed: '_computeExpanded(message.expanded)',
+      },
       _loggedIn: {
         type: Boolean,
         value: false,
@@ -99,19 +99,31 @@
       return !!message.message && loggedIn;
     },
 
+    _computeExpanded: function(expanded) {
+      return expanded;
+    },
+
+    /**
+     * If there is no value set on the message object as to whether _expanded
+     * should be true or not, then _expanded is set to true if there are
+     * inline comments (otherwise false).
+     */
     _commentsChanged: function(value) {
-      this.expanded = Object.keys(value || {}).length > 0;
+      if (this.message && this.message.expanded === undefined) {
+        this.set('message.expanded', Object.keys(value || {}).length > 0);
+      }
     },
 
     _handleTap: function(e) {
-      if (this.expanded) { return; }
-      this.expanded = true;
+      if (this.message.expanded) { return; }
+      e.stopPropagation();
+      this.set('message.expanded', true);
     },
 
     _handleNameTap: function(e) {
-      if (!this.expanded) { return; }
+      if (!this.message.expanded) { return; }
       e.stopPropagation();
-      this.expanded = false;
+      this.set('message.expanded', false);
     },
 
     _computeIsAutomated: function(message) {
diff --git a/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list.js b/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list.js
index 543441a737..fef6307feb 100644
--- a/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list.js
+++ b/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list.js
@@ -45,6 +45,7 @@
       _expanded: {
         type: Boolean,
         value: false,
+        observer: '_expandedChanged',
       },
       _hideAutomated: {
         type: Boolean,
@@ -71,7 +72,7 @@
       var el = this.$$('[data-message-id="' + messageID + '"]');
       if (!el) { return; }
 
-      el.expanded = true;
+      el.set('message.expanded', true);
       var top = el.offsetTop;
       for (var offsetParent = el.offsetParent;
            offsetParent;
@@ -121,6 +122,15 @@
       return result;
     },
 
+    _expandedChanged: function(exp) {
+      for (var i = 0; i < this._processedMessages.length; i++) {
+        this._processedMessages[i].expanded = exp;
+        if (i < this._visibleMessages.length) {
+          this.set(['_visibleMessages', i, 'expanded'], exp);
+        }
+      }
+    },
+
     _highlightEl: function(el) {
       var highlightedEls =
           Polymer.dom(this.root).querySelectorAll('.highlighted');
@@ -136,14 +146,10 @@
     },
 
     /**
-    * @param {boolean} expand
-    */
+     * @param {boolean} expand
+     */
     handleExpandCollapse: function(expand) {
       this._expanded = expand;
-      var messageEls = Polymer.dom(this.root).querySelectorAll('gr-message');
-      for (var i = 0; i < messageEls.length; i++) {
-        messageEls[i].expanded = expand;
-      }
     },
 
     _handleExpandCollapseTap: function(e) {
diff --git a/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list_test.html b/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list_test.html
index 0aaf04a650..09a8fd6d5b 100644
--- a/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list_test.html
+++ b/polygerrit-ui/app/elements/change/gr-messages-list/gr-messages-list_test.html
@@ -122,42 +122,91 @@ limitations under the License.
       assert.isTrue(element.$.messageControlsContainer.hasAttribute('hidden'));
     });
 
+    test('show all messages respects expand', function() {
+      element.messages = _.times(10, randomAutomated)
+          .concat(_.times(11, randomMessage));
+      flushAsynchronousOperations();
+
+      MockInteractions.tap(element.$$('#collapse-messages')); // Expand all.
+      flushAsynchronousOperations();
+
+      var messages = getMessages();
+      assert.equal(messages.length, 20);
+      for (var i = 0; i < messages.length; i++) {
+        assert.isTrue(messages[i]._expanded);
+      }
+
+      MockInteractions.tap(element.$.oldMessagesBtn);
+      flushAsynchronousOperations();
+
+      messages = getMessages();
+      assert.equal(messages.length, 21);
+      for (var i = 0; i < messages.length; i++) {
+        assert.isTrue(messages[i]._expanded);
+      }
+    });
+
+    test('show all messages respects collapse', function() {
+      element.messages = _.times(10, randomAutomated)
+          .concat(_.times(11, randomMessage));
+      flushAsynchronousOperations();
+
+      MockInteractions.tap(element.$$('#collapse-messages')); // Expand all.
+      MockInteractions.tap(element.$$('#collapse-messages')); // Collapse all.
+      flushAsynchronousOperations();
+
+      var messages = getMessages();
+      assert.equal(messages.length, 20);
+      for (var i = 0; i < messages.length; i++) {
+        assert.isFalse(messages[i]._expanded);
+      }
+
+      MockInteractions.tap(element.$.oldMessagesBtn);
+      flushAsynchronousOperations();
+
+      messages = getMessages();
+      assert.equal(messages.length, 21);
+      for (var i = 0; i < messages.length; i++) {
+        assert.isFalse(messages[i]._expanded);
+      }
+    });
+
     test('expand/collapse all', function() {
       var allMessageEls = getMessages();
       for (var i = 0; i < allMessageEls.length; i++) {
-        allMessageEls[i].expanded = false;
+        allMessageEls[i]._expanded = false;
       }
       MockInteractions.tap(allMessageEls[1]);
-      assert.isTrue(allMessageEls[1].expanded);
+      assert.isTrue(allMessageEls[1]._expanded);
 
       MockInteractions.tap(element.$$('#collapse-messages'));
       allMessageEls = getMessages();
       for (var i = 0; i < allMessageEls.length; i++) {
-        assert.isTrue(allMessageEls[i].expanded);
+        assert.isTrue(allMessageEls[i]._expanded);
       }
 
       MockInteractions.tap(element.$$('#collapse-messages'));
       allMessageEls = getMessages();
       for (var i = 0; i < allMessageEls.length; i++) {
-        assert.isFalse(allMessageEls[i].expanded);
+        assert.isFalse(allMessageEls[i]._expanded);
       }
     });
 
     test('expand/collapse from external keypress', function() {
-      element.handleExpandCollapse(true);
+      MockInteractions.tap(element.$$('#collapse-messages'));
       var allMessageEls = getMessages();
       for (var i = 0; i < allMessageEls.length; i++) {
-        assert.isTrue(allMessageEls[i].expanded);
+        assert.isTrue(allMessageEls[i]._expanded);
       }
 
       // Expand/collapse all text also changes.
       assert.equal(element.$$('#collapse-messages').textContent.trim(),
           'Collapse all');
 
-      element.handleExpandCollapse(false);
+      MockInteractions.tap(element.$$('#collapse-messages'));
       allMessageEls = getMessages();
       for (var i = 0; i < allMessageEls.length; i++) {
-        assert.isFalse(allMessageEls[i].expanded);
+        assert.isFalse(allMessageEls[i]._expanded);
       }
       // Expand/collapse all text also changes.
       assert.equal(element.$$('#collapse-messages').textContent.trim(),
@@ -172,7 +221,7 @@ limitations under the License.
     test('scroll to message', function() {
       var allMessageEls = getMessages();
       for (var i = 0; i < allMessageEls.length; i++) {
-        allMessageEls[i].expanded = false;
+        allMessageEls[i].set('message.expanded', false);
       }
 
       var scrollToStub = sinon.stub(window, 'scrollTo');
@@ -181,14 +230,14 @@ limitations under the License.
       element.scrollToMessage('invalid');
 
       for (var i = 0; i < allMessageEls.length; i++) {
-        assert.isFalse(allMessageEls[i].expanded,
+        assert.isFalse(allMessageEls[i]._expanded,
             'expected gr-message ' + i + ' to not be expanded');
       }
 
       var messageID = messages[1].id;
       element.scrollToMessage(messageID);
       assert.isTrue(
-          element.$$('[data-message-id="' + messageID + '"]').expanded);
+          element.$$('[data-message-id="' + messageID + '"]')._expanded);
 
       assert.isTrue(scrollToStub.calledOnce);
       assert.isTrue(highlightStub.calledOnce);