diff --git a/common/static/coffee/spec/discussion/view/thread_response_show_view_spec.coffee b/common/static/coffee/spec/discussion/view/thread_response_show_view_spec.coffee
index 21b0c300f0..c261e085f4 100644
--- a/common/static/coffee/spec/discussion/view/thread_response_show_view_spec.coffee
+++ b/common/static/coffee/spec/discussion/view/thread_response_show_view_spec.coffee
@@ -3,14 +3,38 @@ describe "ThreadResponseShowView", ->
         DiscussionSpecHelper.setUpGlobals()
         setFixtures(
             """
-            <div class="discussion-post">
-                <a href="#" class="vote-btn" data-tooltip="vote" role="button" aria-pressed="false">
-                    <span class="plus-icon"/><span class="votes-count-number">0</span> <span class="sr">votes (click to vote)</span>
+            <script type="text/template" id="thread-response-show-template">
+                <a href="#" class="vote-btn" data-tooltip="vote" role="button" aria-pressed="false"></a>
+                <a
+                    href="javascript:void(0)"
+                    class="endorse-btn action-endorse <%= thread.get('thread_type') == 'question' ? 'mark-answer' : '' %>"
+                    style="cursor: default; display: none;"
+                    data-tooltip="<%= thread.get('thread_type') == 'question' ? 'mark as answer' : 'endorse' %>"
+                >
+                    <span class="check-icon" style="pointer-events: none; "></span>
                 </a>
-            </div>
+                <p class="posted-details">
+                    <span class="timeago" title="<%= created_at %>"><%= created_at %></span>
+                    <% if (thread.get('thread_type') == 'question' && obj.endorsement) { %> -
+                    <%=
+                        interpolate(
+                            endorsement.username ? "marked as answer %(time_ago)s by %(user)s" : "marked as answer %(time_ago)s",
+                            {
+                                'time_ago': '<span class="timeago" title="' + endorsement.time + '">' + endorsement.time + '</span>',
+                                'user': endorsement.username
+                            },
+                            true
+                        )
+                    %>
+                    <% } %>
+                </p>
+            </script>
+
+            <div class="discussion-post"></div>
             """
         )
 
+        @thread = new Thread({"thread_type": "discussion"})
         @commentData = {
             id: "dummy",
             user_id: "567",
@@ -21,9 +45,15 @@ describe "ThreadResponseShowView", ->
             votes: {up_count: "42"}
         }
         @comment = new Comment(@commentData)
+        @comment.set("thread", @thread)
         @view = new ThreadResponseShowView({ model: @comment })
         @view.setElement($(".discussion-post"))
 
+        # Avoid unnecessary boilerplate
+        spyOn(ThreadResponseShowView.prototype, "convertMath")
+
+        @view.render()
+
     it "renders the vote correctly", ->
         DiscussionViewSpecHelper.checkRenderVote(@view, @comment)
 
@@ -38,3 +68,32 @@ describe "ThreadResponseShowView", ->
 
     it "vote button activates on appropriate events", ->
         DiscussionViewSpecHelper.checkVoteButtonEvents(@view)
+
+    it "renders endorsement correctly for a marked answer in a question thread", ->
+        endorsement = {
+          "username": "test_endorser",
+          "time": new Date().toISOString()
+        }
+        @thread.set("thread_type", "question")
+        @comment.set({
+          "endorsed": true,
+          "endorsement": endorsement
+        })
+        @view.render()
+        expect(@view.$(".posted-details").text()).toMatch(
+          "marked as answer less than a minute ago by " + endorsement.username
+        )
+
+    it "renders anonymous endorsement correctly for a marked answer in a question thread", ->
+        endorsement = {
+          "username": null,
+          "time": new Date().toISOString()
+        }
+        @thread.set("thread_type", "question")
+        @comment.set({
+          "endorsed": true,
+          "endorsement": endorsement
+        })
+        @view.render()
+        expect(@view.$(".posted-details").text()).toMatch("marked as answer less than a minute ago")
+        expect(@view.$(".posted-details").text()).not.toMatch(" by ")
diff --git a/common/static/coffee/src/discussion/views/thread_response_show_view.coffee b/common/static/coffee/src/discussion/views/thread_response_show_view.coffee
index 312b660ff6..66e3923153 100644
--- a/common/static/coffee/src/discussion/views/thread_response_show_view.coffee
+++ b/common/static/coffee/src/discussion/views/thread_response_show_view.coffee
@@ -29,7 +29,7 @@ if Backbone?
       @renderVote()
       @renderAttrs()
       @renderFlagged()
-      @$el.find(".posted-details").timeago()
+      @$el.find(".posted-details .timeago").timeago()
       @convertMath()
       @markAsStaff()
       @
diff --git a/lms/djangoapps/django_comment_client/base/views.py b/lms/djangoapps/django_comment_client/base/views.py
index c1e15b6392..3f1f40b577 100644
--- a/lms/djangoapps/django_comment_client/base/views.py
+++ b/lms/djangoapps/django_comment_client/base/views.py
@@ -53,11 +53,11 @@ def permitted(fn):
     return wrapper
 
 
-def ajax_content_response(request, course_id, content):
+def ajax_content_response(request, course_key, content):
     user_info = cc.User.from_django_user(request.user).to_dict()
-    annotated_content_info = get_annotated_content_info(course_id, content, request.user, user_info)
+    annotated_content_info = get_annotated_content_info(course_key, content, request.user, user_info)
     return JsonResponse({
-        'content': safe_content(content),
+        'content': safe_content(content, course_key),
         'annotated_content_info': annotated_content_info,
     })
 
@@ -71,8 +71,8 @@ def create_thread(request, course_id, commentable_id):
     """
 
     log.debug("Creating new thread in %r, id %r", course_id, commentable_id)
-    course_id = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    course = get_course_with_access(request.user, 'load', course_id)
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
+    course = get_course_with_access(request.user, 'load', course_key)
     post = request.POST
 
     if course.allow_anonymous:
@@ -94,7 +94,7 @@ def create_thread(request, course_id, commentable_id):
         anonymous=anonymous,
         anonymous_to_peers=anonymous_to_peers,
         commentable_id=commentable_id,
-        course_id=course_id.to_deprecated_string(),
+        course_id=course_key.to_deprecated_string(),
         user_id=request.user.id,
         body=post["body"],
         title=post["title"]
@@ -107,13 +107,13 @@ def create_thread(request, course_id, commentable_id):
     #not anymore, only for admins
 
     # Cohort the thread if the commentable is cohorted.
-    if is_commentable_cohorted(course_id, commentable_id):
-        user_group_id = get_cohort_id(user, course_id)
+    if is_commentable_cohorted(course_key, commentable_id):
+        user_group_id = get_cohort_id(user, course_key)
 
         # TODO (vshnayder): once we have more than just cohorts, we'll want to
         # change this to a single get_group_for_user_and_commentable function
         # that can do different things depending on the commentable_id
-        if cached_has_permission(request.user, "see_all_cohorts", course_id):
+        if cached_has_permission(request.user, "see_all_cohorts", course_key):
             # admins can optionally choose what group to post as
             group_id = post.get('group_id', user_group_id)
         else:
@@ -135,9 +135,9 @@ def create_thread(request, course_id, commentable_id):
     data = thread.to_dict()
     add_courseware_context([data], course)
     if request.is_ajax():
-        return ajax_content_response(request, course_id, data)
+        return ajax_content_response(request, course_key, data)
     else:
-        return JsonResponse(safe_content(data))
+        return JsonResponse(safe_content(data, course_key))
 
 
 @require_POST
@@ -151,19 +151,20 @@ def update_thread(request, course_id, thread_id):
         return JsonError(_("Title can't be empty"))
     if 'body' not in request.POST or not request.POST['body'].strip():
         return JsonError(_("Body can't be empty"))
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     thread = cc.Thread.find(thread_id)
     thread.body = request.POST["body"]
     thread.title = request.POST["title"]
     thread.save()
     if request.is_ajax():
-        return ajax_content_response(request, SlashSeparatedCourseKey.from_deprecated_string(course_id), thread.to_dict())
+        return ajax_content_response(request, course_key, thread.to_dict())
     else:
-        return JsonResponse(safe_content(thread.to_dict()))
+        return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 def _create_comment(request, course_key, thread_id=None, parent_id=None):
     """
-    given a course_id, thread_id, and parent_id, create a comment,
+    given a course_key, thread_id, and parent_id, create a comment,
     called from create_comment to do the actual creation
     """
     assert isinstance(course_key, CourseKey)
@@ -199,7 +200,7 @@ def _create_comment(request, course_key, thread_id=None, parent_id=None):
     if request.is_ajax():
         return ajax_content_response(request, course_key, comment.to_dict())
     else:
-        return JsonResponse(safe_content(comment.to_dict()))
+        return JsonResponse(safe_content(comment.to_dict(), course.id))
 
 
 @require_POST
@@ -224,9 +225,10 @@ def delete_thread(request, course_id, thread_id):
     given a course_id and thread_id, delete this thread
     this is ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     thread = cc.Thread.find(thread_id)
     thread.delete()
-    return JsonResponse(safe_content(thread.to_dict()))
+    return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 @require_POST
@@ -237,15 +239,16 @@ def update_comment(request, course_id, comment_id):
     given a course_id and comment_id, update the comment with payload attributes
     handles static and ajax submissions
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     comment = cc.Comment.find(comment_id)
     if 'body' not in request.POST or not request.POST['body'].strip():
         return JsonError(_("Body can't be empty"))
     comment.body = request.POST["body"]
     comment.save()
     if request.is_ajax():
-        return ajax_content_response(request, SlashSeparatedCourseKey.from_deprecated_string(course_id), comment.to_dict())
+        return ajax_content_response(request, course_key, comment.to_dict())
     else:
-        return JsonResponse(safe_content(comment.to_dict()))
+        return JsonResponse(safe_content(comment.to_dict(), course_key))
 
 
 @require_POST
@@ -256,10 +259,12 @@ def endorse_comment(request, course_id, comment_id):
     given a course_id and comment_id, toggle the endorsement of this comment,
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     comment = cc.Comment.find(comment_id)
     comment.endorsed = request.POST.get('endorsed', 'false').lower() == 'true'
+    comment.endorsement_user_id = request.user.id
     comment.save()
-    return JsonResponse(safe_content(comment.to_dict()))
+    return JsonResponse(safe_content(comment.to_dict(), course_key))
 
 
 @require_POST
@@ -270,13 +275,14 @@ def openclose_thread(request, course_id, thread_id):
     given a course_id and thread_id, toggle the status of this thread
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     thread = cc.Thread.find(thread_id)
     thread.closed = request.POST.get('closed', 'false').lower() == 'true'
     thread.save()
     thread = thread.to_dict()
     return JsonResponse({
-        'content': safe_content(thread),
-        'ability': get_ability(SlashSeparatedCourseKey.from_deprecated_string(course_id), thread, request.user),
+        'content': safe_content(thread, course_key),
+        'ability': get_ability(course_key, thread, request.user),
     })
 
 
@@ -302,9 +308,10 @@ def delete_comment(request, course_id, comment_id):
     given a course_id and comment_id delete this comment
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     comment = cc.Comment.find(comment_id)
     comment.delete()
-    return JsonResponse(safe_content(comment.to_dict()))
+    return JsonResponse(safe_content(comment.to_dict(), course_key))
 
 
 @require_POST
@@ -314,10 +321,11 @@ def vote_for_comment(request, course_id, comment_id, value):
     """
     given a course_id and comment_id,
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     comment = cc.Comment.find(comment_id)
     user.vote(comment, value)
-    return JsonResponse(safe_content(comment.to_dict()))
+    return JsonResponse(safe_content(comment.to_dict(), course_key))
 
 
 @require_POST
@@ -328,10 +336,11 @@ def undo_vote_for_comment(request, course_id, comment_id):
     given a course id and comment id, remove vote
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     comment = cc.Comment.find(comment_id)
     user.unvote(comment)
-    return JsonResponse(safe_content(comment.to_dict()))
+    return JsonResponse(safe_content(comment.to_dict(), course_key))
 
 
 @require_POST
@@ -342,10 +351,11 @@ def vote_for_thread(request, course_id, thread_id, value):
     given a course id and thread id vote for this thread
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     thread = cc.Thread.find(thread_id)
     user.vote(thread, value)
-    return JsonResponse(safe_content(thread.to_dict()))
+    return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 @require_POST
@@ -356,10 +366,11 @@ def flag_abuse_for_thread(request, course_id, thread_id):
     given a course_id and thread_id flag this thread for abuse
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     thread = cc.Thread.find(thread_id)
     thread.flagAbuse(user, thread)
-    return JsonResponse(safe_content(thread.to_dict()))
+    return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 @require_POST
@@ -371,12 +382,12 @@ def un_flag_abuse_for_thread(request, course_id, thread_id):
     ajax only
     """
     user = cc.User.from_django_user(request.user)
-    course_id = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    course = get_course_by_id(course_id)
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
+    course = get_course_by_id(course_key)
     thread = cc.Thread.find(thread_id)
-    remove_all = cached_has_permission(request.user, 'openclose_thread', course_id) or has_access(request.user, 'staff', course)
+    remove_all = cached_has_permission(request.user, 'openclose_thread', course_key) or has_access(request.user, 'staff', course)
     thread.unFlagAbuse(user, thread, remove_all)
-    return JsonResponse(safe_content(thread.to_dict()))
+    return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 @require_POST
@@ -387,10 +398,11 @@ def flag_abuse_for_comment(request, course_id, comment_id):
     given a course and comment id, flag comment for abuse
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     comment = cc.Comment.find(comment_id)
     comment.flagAbuse(user, comment)
-    return JsonResponse(safe_content(comment.to_dict()))
+    return JsonResponse(safe_content(comment.to_dict(), course_key))
 
 
 @require_POST
@@ -407,7 +419,7 @@ def un_flag_abuse_for_comment(request, course_id, comment_id):
     remove_all = cached_has_permission(request.user, 'openclose_thread', course_key) or has_access(request.user, 'staff', course)
     comment = cc.Comment.find(comment_id)
     comment.unFlagAbuse(user, comment, remove_all)
-    return JsonResponse(safe_content(comment.to_dict()))
+    return JsonResponse(safe_content(comment.to_dict(), course_key))
 
 
 @require_POST
@@ -418,10 +430,11 @@ def undo_vote_for_thread(request, course_id, thread_id):
     given a course id and thread id, remove users vote for thread
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     thread = cc.Thread.find(thread_id)
     user.unvote(thread)
-    return JsonResponse(safe_content(thread.to_dict()))
+    return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 @require_POST
@@ -432,10 +445,11 @@ def pin_thread(request, course_id, thread_id):
     given a course id and thread id, pin this thread
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     thread = cc.Thread.find(thread_id)
     thread.pin(user, thread_id)
-    return JsonResponse(safe_content(thread.to_dict()))
+    return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 @require_POST
@@ -446,10 +460,11 @@ def un_pin_thread(request, course_id, thread_id):
     given a course id and thread id, remove pin from this thread
     ajax only
     """
+    course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
     user = cc.User.from_django_user(request.user)
     thread = cc.Thread.find(thread_id)
     thread.un_pin(user, thread_id)
-    return JsonResponse(safe_content(thread.to_dict()))
+    return JsonResponse(safe_content(thread.to_dict(), course_key))
 
 
 @require_POST
diff --git a/lms/djangoapps/django_comment_client/forum/views.py b/lms/djangoapps/django_comment_client/forum/views.py
index fd3c84feb1..8cef0b6ea8 100644
--- a/lms/djangoapps/django_comment_client/forum/views.py
+++ b/lms/djangoapps/django_comment_client/forum/views.py
@@ -150,7 +150,7 @@ def inline_discussion(request, course_id, discussion_id):
         annotated_content_info = utils.get_metadata_for_threads(course_id, threads, request.user, user_info)
     is_staff = cached_has_permission(request.user, 'openclose_thread', course.id)
     return utils.JsonResponse({
-        'discussion_data': [utils.safe_content(thread, is_staff) for thread in threads],
+        'discussion_data': [utils.safe_content(thread, course_id, is_staff) for thread in threads],
         'user_info': user_info,
         'annotated_content_info': annotated_content_info,
         'page': query_params['page'],
@@ -173,7 +173,7 @@ def forum_form_discussion(request, course_id):
     try:
         unsafethreads, query_params = get_threads(request, course_id)   # This might process a search query
         is_staff = cached_has_permission(request.user, 'openclose_thread', course.id)
-        threads = [utils.safe_content(thread, is_staff) for thread in unsafethreads]
+        threads = [utils.safe_content(thread, course_id, is_staff) for thread in unsafethreads]
     except cc.utils.CommentClientMaintenanceError:
         log.warning("Forum is in maintenance mode")
         return render_to_response('discussion/maintenance.html', {})
@@ -253,7 +253,7 @@ def single_thread(request, course_id, discussion_id, thread_id):
     if request.is_ajax():
         with newrelic.agent.FunctionTrace(nr_transaction, "get_annotated_content_infos"):
             annotated_content_info = utils.get_annotated_content_infos(course_id, thread, request.user, user_info=user_info)
-        content = utils.safe_content(thread.to_dict(), is_staff)
+        content = utils.safe_content(thread.to_dict(), course_id, is_staff)
         with newrelic.agent.FunctionTrace(nr_transaction, "add_courseware_context"):
             add_courseware_context([content], course)
         return utils.JsonResponse({
@@ -276,7 +276,7 @@ def single_thread(request, course_id, discussion_id, thread_id):
             if not "pinned" in thread:
                 thread["pinned"] = False
 
-        threads = [utils.safe_content(thread, is_staff) for thread in threads]
+        threads = [utils.safe_content(thread, course_id, is_staff) for thread in threads]
 
         with newrelic.agent.FunctionTrace(nr_transaction, "get_metadata_for_threads"):
             annotated_content_info = utils.get_metadata_for_threads(course_id, threads, request.user, user_info)
@@ -335,7 +335,7 @@ def user_profile(request, course_id, user_id):
         if request.is_ajax():
             is_staff = cached_has_permission(request.user, 'openclose_thread', course.id)
             return utils.JsonResponse({
-                'discussion_data': [utils.safe_content(thread, is_staff) for thread in threads],
+                'discussion_data': [utils.safe_content(thread, course_id, is_staff) for thread in threads],
                 'page': query_params['page'],
                 'num_pages': query_params['num_pages'],
                 'annotated_content_info': _attr_safe_json(annotated_content_info),
@@ -386,7 +386,7 @@ def followed_threads(request, course_id, user_id):
             is_staff = cached_has_permission(request.user, 'openclose_thread', course.id)
             return utils.JsonResponse({
                 'annotated_content_info': annotated_content_info,
-                'discussion_data': [utils.safe_content(thread, is_staff) for thread in threads],
+                'discussion_data': [utils.safe_content(thread, course_id, is_staff) for thread in threads],
                 'page': query_params['page'],
                 'num_pages': query_params['num_pages'],
             })
diff --git a/lms/djangoapps/django_comment_client/utils.py b/lms/djangoapps/django_comment_client/utils.py
index 9f4065b42b..b31caadf25 100644
--- a/lms/djangoapps/django_comment_client/utils.py
+++ b/lms/djangoapps/django_comment_client/utils.py
@@ -9,7 +9,7 @@ from django.db import connection
 from django.http import HttpResponse
 from django.utils import simplejson
 from django_comment_common.models import Role, FORUM_ROLE_STUDENT
-from django_comment_client.permissions import check_permissions_by_view
+from django_comment_client.permissions import check_permissions_by_view, cached_has_permission
 
 from edxmako import lookup_template
 import pystache_custom as pystache
@@ -365,7 +365,7 @@ def add_courseware_context(content_list, course):
             content.update({"courseware_url": url, "courseware_title": title})
 
 
-def safe_content(content, is_staff=False):
+def safe_content(content, course_id, is_staff=False):
     fields = [
         'id', 'title', 'body', 'course_id', 'anonymous', 'anonymous_to_peers',
         'endorsed', 'parent_id', 'thread_id', 'votes', 'closed', 'created_at',
@@ -375,14 +375,40 @@ def safe_content(content, is_staff=False):
         'read', 'group_id', 'group_name', 'group_string', 'pinned', 'abuse_flaggers',
         'stats', 'resp_skip', 'resp_limit', 'resp_total', 'thread_type',
         'endorsed_responses', 'non_endorsed_responses', 'non_endorsed_resp_total',
+        'endorsement',
     ]
 
     if (content.get('anonymous') is False) and ((content.get('anonymous_to_peers') is False) or is_staff):
         fields += ['username', 'user_id']
 
+    content = strip_none(extract(content, fields))
+
+    if content.get("endorsement"):
+        endorsement = content["endorsement"]
+        endorser = None
+        if endorsement["user_id"]:
+            try:
+                endorser = User.objects.get(pk=endorsement["user_id"])
+            except User.DoesNotExist:
+                log.error("User ID {0} in endorsement for comment {1} but not in our DB.".format(
+                    content.get('user_id'),
+                    content.get('id'))
+                )
+
+        # Only reveal endorser if requester can see author or if endorser is staff
+        if (
+            endorser and
+            ("username" in fields or cached_has_permission(endorser, "endorse_comment", course_id))
+        ):
+            endorsement["username"] = endorser.username
+        else:
+            del endorsement["user_id"]
+
     for child_content_key in ["children", "endorsed_responses", "non_endorsed_responses"]:
         if child_content_key in content:
-            safe_children = [safe_content(child) for child in content[child_content_key]]
+            safe_children = [
+                safe_content(child, course_id, is_staff) for child in content[child_content_key]
+            ]
             content[child_content_key] = safe_children
 
-    return strip_none(extract(content, fields))
+    return content
diff --git a/lms/lib/comment_client/comment.py b/lms/lib/comment_client/comment.py
index 3082b1dcc8..febb533b33 100644
--- a/lms/lib/comment_client/comment.py
+++ b/lms/lib/comment_client/comment.py
@@ -11,12 +11,12 @@ class Comment(models.Model):
         'id', 'body', 'anonymous', 'anonymous_to_peers', 'course_id',
         'endorsed', 'parent_id', 'thread_id', 'username', 'votes', 'user_id',
         'closed', 'created_at', 'updated_at', 'depth', 'at_position_list',
-        'type', 'commentable_id', 'abuse_flaggers'
+        'type', 'commentable_id', 'abuse_flaggers', 'endorsement',
     ]
 
     updatable_fields = [
         'body', 'anonymous', 'anonymous_to_peers', 'course_id', 'closed',
-        'user_id', 'endorsed'
+        'user_id', 'endorsed', 'endorsement_user_id',
     ]
 
     initializable_fields = updatable_fields
diff --git a/lms/lib/comment_client/models.py b/lms/lib/comment_client/models.py
index 5a9eb740f3..555fca883a 100644
--- a/lms/lib/comment_client/models.py
+++ b/lms/lib/comment_client/models.py
@@ -35,7 +35,7 @@ class Model(object):
             return self.__getattr__(name)
 
     def __setattr__(self, name, value):
-        if name == 'attributes' or name not in self.accessible_fields:
+        if name == 'attributes' or name not in (self.accessible_fields + self.updatable_fields):
             super(Model, self).__setattr__(name, value)
         else:
             self.attributes[name] = value
@@ -46,7 +46,7 @@ class Model(object):
         return self.attributes.get(key)
 
     def __setitem__(self, key, value):
-        if key not in self.accessible_fields:
+        if key not in (self.accessible_fields + self.updatable_fields):
             raise KeyError("Field {0} does not exist".format(key))
         self.attributes.__setitem__(key, value)
 
diff --git a/lms/static/sass/discussion/_discussion.scss b/lms/static/sass/discussion/_discussion.scss
index 26d2d5a087..d05e9b9674 100644
--- a/lms/static/sass/discussion/_discussion.scss
+++ b/lms/static/sass/discussion/_discussion.scss
@@ -441,7 +441,8 @@ body.discussion {
         font-weight: 700;
       }
 
-      span {
+      .timeago, .top-post-status {
+        color: inherit;
         font-style: italic;
       }
     }
diff --git a/lms/templates/discussion/_underscore_templates.html b/lms/templates/discussion/_underscore_templates.html
index bd090b7f74..a3aa6ab622 100644
--- a/lms/templates/discussion/_underscore_templates.html
+++ b/lms/templates/discussion/_underscore_templates.html
@@ -159,7 +159,28 @@
         ${"<% } else { %>"}
         <span class="anonymous"><em>${_('anonymous')}</em></span>
         ${"<% } %>"}
-        <p class="posted-details" title="${'<%- created_at %>'}">${'<%- created_at %>'}</p>
+        <p class="posted-details">
+            <span class="timeago" title="${'<%= created_at %>'}">${'<%= created_at %>'}</span>
+            <%
+            js_block = u"""
+                interpolate(
+                    endorsement.username ? "{user_fmt_str}" : "{anon_fmt_str}",
+                    {{
+                        'time_ago': '<span class="timeago" title="' + endorsement.time + '">' + endorsement.time + '</span>',
+                        'user': endorsement.username
+                    }},
+                    true
+                )""".format(
+                    ## Translators: time_ago is a placeholder for a fuzzy, relative timestamp
+                    ## like "4 hours ago" or "about a month ago"
+                    user_fmt_str=escapejs(_("marked as answer %(time_ago)s by %(user)s")),
+                    ## Translators: time_ago is a placeholder for a fuzzy, relative timestamp
+                    ## like "4 hours ago" or "about a month ago"
+                    anon_fmt_str=escapejs(_("marked as answer %(time_ago)s")),
+                )
+            %>
+            ${"<% if (thread.get('thread_type') == 'question' && obj.endorsement) { %> - <%="}${js_block}${"%><% } %>"}
+        </p>
     </header>
     <div class="response-body">${"<%- body %>"}</div>
     <div class="discussion-flag-abuse notflagged" data-role="thread-flag" role="button" aria-pressed="false" tabindex="0">