diff --git a/lms/djangoapps/discussion_api/__init__.py b/lms/djangoapps/discussion_api/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/lms/djangoapps/discussion_api/api.py b/lms/djangoapps/discussion_api/api.py
new file mode 100644
index 0000000000..21034f5aa7
--- /dev/null
+++ b/lms/djangoapps/discussion_api/api.py
@@ -0,0 +1,65 @@
+"""
+Discussion API internal interface
+"""
+from collections import defaultdict
+
+from django_comment_client.utils import get_accessible_discussion_modules
+
+
+def get_course_topics(course, user):
+    """
+    Return the course topic listing for the given course and user.
+
+    Parameters:
+
+    course: The course to get topics for
+    user: The requesting user, for access control
+
+    Returns:
+
+    A course topic listing dictionary; see discussion_api.views.CourseTopicViews
+    for more detail.
+    """
+    def get_module_sort_key(module):
+        """
+        Get the sort key for the module (falling back to the discussion_target
+        setting if absent)
+        """
+        return module.sort_key or module.discussion_target
+
+    discussion_modules = get_accessible_discussion_modules(course, user)
+    modules_by_category = defaultdict(list)
+    for module in discussion_modules:
+        modules_by_category[module.discussion_category].append(module)
+    courseware_topics = [
+        {
+            "id": None,
+            "name": category,
+            "children": [
+                {
+                    "id": module.discussion_id,
+                    "name": module.discussion_target,
+                    "children": [],
+                }
+                for module in sorted(modules_by_category[category], key=get_module_sort_key)
+            ],
+        }
+        for category in sorted(modules_by_category.keys())
+    ]
+
+    non_courseware_topics = [
+        {
+            "id": entry["id"],
+            "name": name,
+            "children": [],
+        }
+        for name, entry in sorted(
+            course.discussion_topics.items(),
+            key=lambda item: item[1].get("sort_key", item[0])
+        )
+    ]
+
+    return {
+        "courseware_topics": courseware_topics,
+        "non_courseware_topics": non_courseware_topics,
+    }
diff --git a/lms/djangoapps/discussion_api/models.py b/lms/djangoapps/discussion_api/models.py
new file mode 100644
index 0000000000..d2e8572729
--- /dev/null
+++ b/lms/djangoapps/discussion_api/models.py
@@ -0,0 +1,3 @@
+"""
+A models.py is required to make this an app (until we move to Django 1.7)
+"""
diff --git a/lms/djangoapps/discussion_api/tests/test_api.py b/lms/djangoapps/discussion_api/tests/test_api.py
new file mode 100644
index 0000000000..7b034183f6
--- /dev/null
+++ b/lms/djangoapps/discussion_api/tests/test_api.py
@@ -0,0 +1,306 @@
+"""
+Tests for Discussion API internal interface
+"""
+from datetime import datetime, timedelta
+
+import mock
+from pytz import UTC
+
+from courseware.tests.factories import BetaTesterFactory, StaffFactory
+from discussion_api.api import get_course_topics
+from openedx.core.djangoapps.course_groups.models import CourseUserGroupPartitionGroup
+from openedx.core.djangoapps.course_groups.tests.helpers import CohortFactory
+from student.tests.factories import UserFactory
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
+from xmodule.partitions.partitions import Group, UserPartition
+
+
+@mock.patch.dict("django.conf.settings.FEATURES", {"DISABLE_START_DATES": False})
+class GetCourseTopicsTest(ModuleStoreTestCase):
+    """Test for get_course_topics"""
+
+    def setUp(self):
+        super(GetCourseTopicsTest, self).setUp()
+        self.maxDiff = None  # pylint: disable=invalid-name
+        self.partition = UserPartition(
+            0,
+            "partition",
+            "Test Partition",
+            [Group(0, "Cohort A"), Group(1, "Cohort B")],
+            scheme_id="cohort"
+        )
+        self.course = CourseFactory.create(
+            org="x",
+            course="y",
+            run="z",
+            start=datetime.now(UTC),
+            discussion_topics={},
+            user_partitions=[self.partition],
+            cohort_config={"cohorted": True},
+            days_early_for_beta=3
+        )
+        self.user = UserFactory.create()
+
+    def make_discussion_module(self, topic_id, category, subcategory, **kwargs):
+        """Build a discussion module in self.course"""
+        ItemFactory.create(
+            parent_location=self.course.location,
+            category="discussion",
+            discussion_id=topic_id,
+            discussion_category=category,
+            discussion_target=subcategory,
+            **kwargs
+        )
+
+    def get_course_topics(self, user=None):
+        """
+        Get course topics for self.course, using the given user or self.user if
+        not provided, and generating absolute URIs with a test scheme/host.
+        """
+        return get_course_topics(self.course, user or self.user)
+
+    def make_expected_tree(self, topic_id, name, children=None):
+        """
+        Build an expected result tree given a topic id, display name, and
+        children
+        """
+        children = children or []
+        node = {
+            "id": topic_id,
+            "name": name,
+            "children": children,
+        }
+        return node
+
+    def test_empty(self):
+        actual = self.get_course_topics()
+        expected = {
+            "courseware_topics": [],
+            "non_courseware_topics": [],
+        }
+        self.assertEqual(actual, expected)
+
+    def test_non_courseware(self):
+        self.course.discussion_topics = {"Topic Name": {"id": "topic-id"}}
+        self.course.save()
+        actual = self.get_course_topics()
+        expected = {
+            "courseware_topics": [],
+            "non_courseware_topics": [self.make_expected_tree("topic-id", "Topic Name")],
+        }
+        self.assertEqual(actual, expected)
+
+    def test_courseware(self):
+        self.make_discussion_module("topic-id", "Foo", "Bar")
+        actual = self.get_course_topics()
+        expected = {
+            "courseware_topics": [
+                self.make_expected_tree(
+                    None,
+                    "Foo",
+                    [self.make_expected_tree("topic-id", "Bar")]
+                ),
+            ],
+            "non_courseware_topics": [],
+        }
+        self.assertEqual(actual, expected)
+
+    def test_many(self):
+        self.make_discussion_module("courseware-1", "A", "1")
+        self.make_discussion_module("courseware-2", "A", "2")
+        self.make_discussion_module("courseware-3", "B", "1")
+        self.make_discussion_module("courseware-4", "B", "2")
+        self.make_discussion_module("courseware-5", "C", "1")
+        self.course.discussion_topics = {
+            "A": {"id": "non-courseware-1"},
+            "B": {"id": "non-courseware-2"},
+        }
+        self.course.save()
+        actual = self.get_course_topics()
+        expected = {
+            "courseware_topics": [
+                self.make_expected_tree(
+                    None,
+                    "A",
+                    [
+                        self.make_expected_tree("courseware-1", "1"),
+                        self.make_expected_tree("courseware-2", "2"),
+                    ]
+                ),
+                self.make_expected_tree(
+                    None,
+                    "B",
+                    [
+                        self.make_expected_tree("courseware-3", "1"),
+                        self.make_expected_tree("courseware-4", "2"),
+                    ]
+                ),
+                self.make_expected_tree(
+                    None,
+                    "C",
+                    [self.make_expected_tree("courseware-5", "1")]
+                ),
+            ],
+            "non_courseware_topics": [
+                self.make_expected_tree("non-courseware-1", "A"),
+                self.make_expected_tree("non-courseware-2", "B"),
+            ],
+        }
+        self.assertEqual(actual, expected)
+
+    def test_sort_key(self):
+        self.make_discussion_module("courseware-1", "First", "A", sort_key="D")
+        self.make_discussion_module("courseware-2", "First", "B", sort_key="B")
+        self.make_discussion_module("courseware-3", "First", "C", sort_key="E")
+        self.make_discussion_module("courseware-4", "Second", "A", sort_key="F")
+        self.make_discussion_module("courseware-5", "Second", "B", sort_key="G")
+        self.make_discussion_module("courseware-6", "Second", "C")
+        self.make_discussion_module("courseware-7", "Second", "D", sort_key="A")
+        self.course.discussion_topics = {
+            "W": {"id": "non-courseware-1", "sort_key": "Z"},
+            "X": {"id": "non-courseware-2"},
+            "Y": {"id": "non-courseware-3", "sort_key": "Y"},
+            "Z": {"id": "non-courseware-4", "sort_key": "W"},
+        }
+        self.course.save()
+        actual = self.get_course_topics()
+        expected = {
+            "courseware_topics": [
+                self.make_expected_tree(
+                    None,
+                    "First",
+                    [
+                        self.make_expected_tree("courseware-2", "B"),
+                        self.make_expected_tree("courseware-1", "A"),
+                        self.make_expected_tree("courseware-3", "C"),
+                    ]
+                ),
+                self.make_expected_tree(
+                    None,
+                    "Second",
+                    [
+                        self.make_expected_tree("courseware-7", "D"),
+                        self.make_expected_tree("courseware-6", "C"),
+                        self.make_expected_tree("courseware-4", "A"),
+                        self.make_expected_tree("courseware-5", "B"),
+                    ]
+                ),
+            ],
+            "non_courseware_topics": [
+                self.make_expected_tree("non-courseware-4", "Z"),
+                self.make_expected_tree("non-courseware-2", "X"),
+                self.make_expected_tree("non-courseware-3", "Y"),
+                self.make_expected_tree("non-courseware-1", "W"),
+            ],
+        }
+        self.assertEqual(actual, expected)
+
+    def test_access_control(self):
+        """
+        Test that only topics that a user has access to are returned. The
+        ways in which a user may not have access are:
+
+        * Module is visible to staff only
+        * Module has a start date in the future
+        * Module is accessible only to a group the user is not in
+
+        Also, there is a case that ensures that a category with no accessible
+        subcategories does not appear in the result.
+        """
+        beta_tester = BetaTesterFactory.create(course_key=self.course.id)
+        staff = StaffFactory.create(course_key=self.course.id)
+        for user, group_idx in [(self.user, 0), (beta_tester, 1)]:
+            cohort = CohortFactory.create(
+                course_id=self.course.id,
+                name=self.partition.groups[group_idx].name,
+                users=[user]
+            )
+            CourseUserGroupPartitionGroup.objects.create(
+                course_user_group=cohort,
+                partition_id=self.partition.id,
+                group_id=self.partition.groups[group_idx].id
+            )
+
+        self.make_discussion_module("courseware-1", "First", "Everybody")
+        self.make_discussion_module(
+            "courseware-2",
+            "First",
+            "Cohort A",
+            group_access={self.partition.id: [self.partition.groups[0].id]}
+        )
+        self.make_discussion_module(
+            "courseware-3",
+            "First",
+            "Cohort B",
+            group_access={self.partition.id: [self.partition.groups[1].id]}
+        )
+        self.make_discussion_module("courseware-4", "Second", "Staff Only", visible_to_staff_only=True)
+        self.make_discussion_module(
+            "courseware-5",
+            "Second",
+            "Future Start Date",
+            start=datetime.now(UTC) + timedelta(days=1)
+        )
+
+        student_actual = self.get_course_topics()
+        student_expected = {
+            "courseware_topics": [
+                self.make_expected_tree(
+                    None,
+                    "First",
+                    [
+                        self.make_expected_tree("courseware-2", "Cohort A"),
+                        self.make_expected_tree("courseware-1", "Everybody"),
+                    ]
+                ),
+            ],
+            "non_courseware_topics": [],
+        }
+        self.assertEqual(student_actual, student_expected)
+
+        beta_actual = self.get_course_topics(beta_tester)
+        beta_expected = {
+            "courseware_topics": [
+                self.make_expected_tree(
+                    None,
+                    "First",
+                    [
+                        self.make_expected_tree("courseware-3", "Cohort B"),
+                        self.make_expected_tree("courseware-1", "Everybody"),
+                    ]
+                ),
+                self.make_expected_tree(
+                    None,
+                    "Second",
+                    [self.make_expected_tree("courseware-5", "Future Start Date")]
+                ),
+            ],
+            "non_courseware_topics": [],
+        }
+        self.assertEqual(beta_actual, beta_expected)
+
+        staff_actual = self.get_course_topics(staff)
+        staff_expected = {
+            "courseware_topics": [
+                self.make_expected_tree(
+                    None,
+                    "First",
+                    [
+                        self.make_expected_tree("courseware-2", "Cohort A"),
+                        self.make_expected_tree("courseware-3", "Cohort B"),
+                        self.make_expected_tree("courseware-1", "Everybody"),
+                    ]
+                ),
+                self.make_expected_tree(
+                    None,
+                    "Second",
+                    [
+                        self.make_expected_tree("courseware-5", "Future Start Date"),
+                        self.make_expected_tree("courseware-4", "Staff Only"),
+                    ]
+                ),
+            ],
+            "non_courseware_topics": [],
+        }
+        self.assertEqual(staff_actual, staff_expected)
diff --git a/lms/djangoapps/discussion_api/tests/test_views.py b/lms/djangoapps/discussion_api/tests/test_views.py
new file mode 100644
index 0000000000..c6d213963e
--- /dev/null
+++ b/lms/djangoapps/discussion_api/tests/test_views.py
@@ -0,0 +1,100 @@
+"""
+Tests for Discussion API views
+"""
+from datetime import datetime
+import json
+
+import mock
+from pytz import UTC
+
+from django.core.urlresolvers import reverse
+
+from student.tests.factories import CourseEnrollmentFactory, UserFactory
+from util.testing import UrlResetMixin
+from xmodule.modulestore.django import modulestore
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.tests.factories import CourseFactory
+from xmodule.tabs import DiscussionTab
+
+
+class CourseTopicsViewTest(UrlResetMixin, ModuleStoreTestCase):
+    """Tests for CourseTopicsView"""
+
+    @mock.patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": True})
+    def setUp(self):
+        super(CourseTopicsViewTest, self).setUp()
+        self.maxDiff = None  # pylint: disable=invalid-name
+        self.course = CourseFactory.create(
+            org="x",
+            course="y",
+            run="z",
+            start=datetime.now(UTC),
+            discussion_topics={"Test Topic": {"id": "test_topic"}}
+        )
+        self.password = "password"
+        self.user = UserFactory.create(password=self.password)
+        CourseEnrollmentFactory.create(user=self.user, course_id=self.course.id)
+        self.url = reverse("course_topics", kwargs={"course_id": unicode(self.course.id)})
+        self.client.login(username=self.user.username, password=self.password)
+
+    def assert_response_correct(self, response, expected_status, expected_content):
+        """
+        Assert that the response has the given status code and parsed content
+        """
+        self.assertEqual(response.status_code, expected_status)
+        parsed_content = json.loads(response.content)
+        self.assertEqual(parsed_content, expected_content)
+
+    def test_not_authenticated(self):
+        self.client.logout()
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            401,
+            {"developer_message": "Authentication credentials were not provided."}
+        )
+
+    def test_non_existent_course(self):
+        response = self.client.get(
+            reverse("course_topics", kwargs={"course_id": "non/existent/course"})
+        )
+        self.assert_response_correct(
+            response,
+            404,
+            {"developer_message": "Not found."}
+        )
+
+    def test_not_enrolled(self):
+        unenrolled_user = UserFactory.create(password=self.password)
+        self.client.login(username=unenrolled_user.username, password=self.password)
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            404,
+            {"developer_message": "Not found."}
+        )
+
+    def test_discussions_disabled(self):
+        self.course.tabs = [tab for tab in self.course.tabs if not isinstance(tab, DiscussionTab)]
+        modulestore().update_item(self.course, self.user.id)
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            404,
+            {"developer_message": "Not found."}
+        )
+
+    def test_get(self):
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            200,
+            {
+                "courseware_topics": [],
+                "non_courseware_topics": [{
+                    "id": "test_topic",
+                    "name": "Test Topic",
+                    "children": []
+                }],
+            }
+        )
diff --git a/lms/djangoapps/discussion_api/urls.py b/lms/djangoapps/discussion_api/urls.py
new file mode 100644
index 0000000000..2f023eda57
--- /dev/null
+++ b/lms/djangoapps/discussion_api/urls.py
@@ -0,0 +1,17 @@
+"""
+Discussion API URLs
+"""
+from django.conf import settings
+from django.conf.urls import patterns, url
+
+from discussion_api.views import CourseTopicsView
+
+
+urlpatterns = patterns(
+    "discussion_api",
+    url(
+        r"^v1/course_topics/{}".format(settings.COURSE_ID_PATTERN),
+        CourseTopicsView.as_view(),
+        name="course_topics"
+    ),
+)
diff --git a/lms/djangoapps/discussion_api/views.py b/lms/djangoapps/discussion_api/views.py
new file mode 100644
index 0000000000..f9d82f8b58
--- /dev/null
+++ b/lms/djangoapps/discussion_api/views.py
@@ -0,0 +1,54 @@
+"""
+Discussion API views
+"""
+from django.http import Http404
+
+from rest_framework.authentication import OAuth2Authentication, SessionAuthentication
+from rest_framework.permissions import IsAuthenticated
+from rest_framework.response import Response
+from rest_framework.views import APIView
+
+from opaque_keys.edx.locator import CourseLocator
+
+from courseware.courses import get_course_with_access
+from discussion_api.api import get_course_topics
+from openedx.core.lib.api.view_utils import DeveloperErrorViewMixin
+from xmodule.tabs import DiscussionTab
+
+
+class CourseTopicsView(DeveloperErrorViewMixin, APIView):
+    """
+    **Use Cases**
+
+        Retrieve the topic listing for a course. Only topics accessible to the
+        authenticated user are included.
+
+    **Example Requests**:
+
+        GET /api/discussion/v1/course_topics/{course_id}
+
+    **Response Values**:
+
+        * courseware_topics: The list of topic trees for courseware-linked
+          topics. Each item in the list includes:
+
+            * id: The id of the discussion topic (null for a topic that only
+              has children but cannot contain threads itself).
+
+            * name: The display name of the topic.
+
+            * children: A list of child subtrees of the same format.
+
+        * non_courseware_topics: The list of topic trees that are not linked to
+              courseware. Items are of the same format as in courseware_topics.
+    """
+    authentication_classes = (OAuth2Authentication, SessionAuthentication)
+    permission_classes = (IsAuthenticated,)
+
+    def get(self, request, course_id):
+        """Implements the GET method as described in the class docstring."""
+        course_key = CourseLocator.from_string(course_id)
+        course = get_course_with_access(request.user, 'load_forum', course_key)
+        if not any([isinstance(tab, DiscussionTab) for tab in course.tabs]):
+            raise Http404
+        return Response(get_course_topics(course, request.user))
diff --git a/lms/envs/common.py b/lms/envs/common.py
index ac4e49cb7a..99add8d9b2 100644
--- a/lms/envs/common.py
+++ b/lms/envs/common.py
@@ -1657,6 +1657,7 @@ INSTALLED_APPS = (
     # Discussion forums
     'django_comment_client',
     'django_comment_common',
+    'discussion_api',
     'notes',
 
     'edxnotes',
diff --git a/lms/urls.py b/lms/urls.py
index c359412e97..d1baa5e6b3 100644
--- a/lms/urls.py
+++ b/lms/urls.py
@@ -443,6 +443,7 @@ if settings.COURSEWARE_ENABLED:
     # discussion forums live within courseware, so courseware must be enabled first
     if settings.FEATURES.get('ENABLE_DISCUSSION_SERVICE'):
         urlpatterns += (
+            url(r'^api/discussion/', include('discussion_api.urls')),
             url(r'^courses/{}/discussion/'.format(settings.COURSE_ID_PATTERN),
                 include('django_comment_client.urls')),
             url(r'^notification_prefs/enable/', 'notification_prefs.views.ajax_enable'),
diff --git a/openedx/core/lib/api/view_utils.py b/openedx/core/lib/api/view_utils.py
new file mode 100644
index 0000000000..9ab8c57135
--- /dev/null
+++ b/openedx/core/lib/api/view_utils.py
@@ -0,0 +1,28 @@
+"""
+Utilities related to API views
+"""
+from django.http import Http404
+
+from rest_framework.exceptions import APIException
+from rest_framework.response import Response
+
+
+class DeveloperErrorViewMixin(object):
+    """
+    A view mixin to handle common error cases other than validation failure
+    (auth failure, method not allowed, etc.) by generating an error response
+    conforming to our API conventions with a developer message.
+    """
+    def make_error_response(self, status_code, developer_message):
+        """
+        Build an error response with the given status code and developer_message
+        """
+        return Response({"developer_message": developer_message}, status=status_code)
+
+    def handle_exception(self, exc):
+        if isinstance(exc, APIException):
+            return self.make_error_response(exc.status_code, exc.detail)
+        elif isinstance(exc, Http404):
+            return self.make_error_response(404, "Not found.")
+        else:
+            raise