diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 501baee768..fbdbb611a3 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -12,6 +12,14 @@ Blades: Fix bug when image response in Firefox does not retain input. BLD-711.
 
 Blades: Give numerical response tolerance as a range. BLD-25.
 
+Common: Add a utility app for building databased-backed configuration
+  for specific application features. Includes admin site customization
+  for easier administration and tracking.
+
+Common: Add the ability to dark-launch site translations. These languages
+  will be unavailable to users except through the use of a specific query
+  parameter.
+
 Blades: Allow user with BetaTester role correctly use LTI. BLD-641.
 
 Blades: Video player persist speed preferences between videos. BLD-237.
diff --git a/cms/envs/aws.py b/cms/envs/aws.py
index a781576455..555fa39ec0 100644
--- a/cms/envs/aws.py
+++ b/cms/envs/aws.py
@@ -153,6 +153,11 @@ COURSES_WITH_UNSAFE_CODE = ENV_TOKENS.get("COURSES_WITH_UNSAFE_CODE", [])
 #Timezone overrides
 TIME_ZONE = ENV_TOKENS.get('TIME_ZONE', TIME_ZONE)
 
+# Translation overrides
+LANGUAGES = ENV_TOKENS.get('LANGUAGES', LANGUAGES)
+LANGUAGE_CODE = ENV_TOKENS.get('LANGUAGE_CODE', LANGUAGE_CODE)
+USE_I18N = ENV_TOKENS.get('USE_I18N', USE_I18N)
+
 ENV_FEATURES = ENV_TOKENS.get('FEATURES', ENV_TOKENS.get('MITX_FEATURES', {}))
 for feature, value in ENV_FEATURES.items():
     FEATURES[feature] = value
diff --git a/cms/envs/common.py b/cms/envs/common.py
index 4dc75f87e9..bd19b365b9 100644
--- a/cms/envs/common.py
+++ b/cms/envs/common.py
@@ -167,6 +167,9 @@ MIDDLEWARE_CLASSES = (
     'django.contrib.messages.middleware.MessageMiddleware',
     'track.middleware.TrackMiddleware',
 
+    # Allows us to dark-launch particular languages
+    'dark_lang.middleware.DarkLangMiddleware',
+
     # Detects user-requested locale from 'accept-language' header in http request
     'django.middleware.locale.LocaleMiddleware',
 
@@ -244,12 +247,11 @@ STATICFILES_DIRS = [
 TIME_ZONE = 'America/New_York'  # http://en.wikipedia.org/wiki/List_of_tz_zones_by_name
 LANGUAGE_CODE = 'en'  # http://www.i18nguy.com/unicode/language-identifiers.html
 
-# We want i18n to be turned off in production, at least until we have full localizations.
-# Thus we want the Django translation engine to be disabled. Otherwise even without
-# localization files, if the user's browser is set to a language other than us-en,
-# strings like "login" and "password" will be translated and the rest of the page will be
-# in English, which is confusing.
-USE_I18N = False
+LANGUAGES = (
+    ('eo', 'Esperanto'),
+)
+
+USE_I18N = True
 USE_L10N = True
 
 # Localization strings (e.g. django.po) are under this directory
@@ -406,6 +408,9 @@ INSTALLED_APPS = (
     'south',
     'method_override',
 
+    # Database-backed configuration
+    'config_models',
+
     # Monitor the status of services
     'service_status',
 
@@ -438,7 +443,10 @@ INSTALLED_APPS = (
     'django.contrib.admin',
 
     # for managing course modes
-    'course_modes'
+    'course_modes',
+
+    # Dark-launching languages
+    'dark_lang',
 )
 
 
diff --git a/cms/envs/dev.py b/cms/envs/dev.py
index 16efed18c8..cd3e2067f4 100644
--- a/cms/envs/dev.py
+++ b/cms/envs/dev.py
@@ -9,11 +9,6 @@ from .common import *
 from logsettings import get_logger_config
 
 DEBUG = True
-USE_I18N = True
-# For displaying the dummy text, we need to provide a language mapping.
-LANGUAGES = (
-    ('eo', 'Esperanto'),
-)
 TEMPLATE_DEBUG = DEBUG
 LOGGING = get_logger_config(ENV_ROOT / "log",
                             logging_env="dev",
diff --git a/common/djangoapps/config_models/README.rst b/common/djangoapps/config_models/README.rst
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/common/djangoapps/config_models/__init__.py b/common/djangoapps/config_models/__init__.py
new file mode 100644
index 0000000000..3f71f1c98e
--- /dev/null
+++ b/common/djangoapps/config_models/__init__.py
@@ -0,0 +1,62 @@
+"""
+Model-Based Configuration
+=========================
+
+This app allows other apps to easily define a configuration model
+that can be hooked into the admin site to allow configuration management
+with auditing.
+
+Installation
+------------
+
+Add ``config_models`` to your ``INSTALLED_APPS`` list.
+
+Usage
+-----
+
+Create a subclass of ``ConfigurationModel``, with fields for each
+value that needs to be configured::
+
+    class MyConfiguration(ConfigurationModel):
+        frobble_timeout = IntField(default=10)
+        frazzle_target = TextField(defalut="debug")
+
+This is a normal django model, so it must be synced and migrated as usual.
+
+The default values for the fields in the ``ConfigurationModel`` will be
+used if no configuration has yet been created.
+
+Register that class with the Admin site, using the ``ConfigurationAdminModel``::
+
+    from django.contrib import admin
+
+    from config_models.admin import ConfigurationModelAdmin
+
+    admin.site.register(MyConfiguration, ConfigurationModelAdmin)
+
+Use the configuration in your code::
+
+    def my_view(self, request):
+        config = MyConfiguration.current()
+        fire_the_missiles(config.frazzle_target, timeout=config.frobble_timeout)
+
+Use the admin site to add new configuration entries. The most recently created
+entry is considered to be ``current``.
+
+Configuration
+-------------
+
+The current ``ConfigurationModel`` will be cached in the ``configuration`` django cache,
+or in the ``default`` cache if ``configuration`` doesn't exist. You can specify the cache
+timeout in each ``ConfigurationModel`` by setting the ``cache_timeout`` property.
+
+You can change the name of the cache key used by the ``ConfigurationModel`` by overriding
+the ``cache_key_name`` function.
+
+Extension
+---------
+
+``ConfigurationModels`` are just django models, so they can be extended with new fields
+and migrated as usual. Newly added fields must have default values and should be nullable,
+so that rollbacks to old versions of configuration work correctly.
+"""
diff --git a/common/djangoapps/config_models/admin.py b/common/djangoapps/config_models/admin.py
new file mode 100644
index 0000000000..378900f1dc
--- /dev/null
+++ b/common/djangoapps/config_models/admin.py
@@ -0,0 +1,80 @@
+"""
+Admin site models for managing :class:`.ConfigurationModel` subclasses
+"""
+
+from django.forms import models
+from django.contrib import admin
+from django.http import HttpResponseRedirect
+from django.core.urlresolvers import reverse
+
+# pylint: disable=protected-access
+
+
+class ConfigurationModelAdmin(admin.ModelAdmin):
+    """
+    :class:`~django.contrib.admin.ModelAdmin` for :class:`.ConfigurationModel` subclasses
+    """
+    date_hierarchy = 'change_date'
+
+    def get_actions(self, request):
+        return {
+            'revert': (ConfigurationModelAdmin.revert, 'revert', 'Revert to the selected configuration')
+        }
+
+    def get_list_display(self, request):
+        return self.model._meta.get_all_field_names()
+
+    # Don't allow deletion of configuration
+    def has_delete_permission(self, request, obj=None):
+        return False
+
+    # Make all fields read-only when editing an object
+    def get_readonly_fields(self, request, obj=None):
+        if obj:  # editing an existing object
+            return self.model._meta.get_all_field_names()
+        return self.readonly_fields
+
+    def add_view(self, request, form_url='', extra_context=None):
+        # Prepopulate new configuration entries with the value of the current config
+        get = request.GET.copy()
+        get.update(models.model_to_dict(self.model.current()))
+        request.GET = get
+        return super(ConfigurationModelAdmin, self).add_view(request, form_url, extra_context)
+
+    # Hide the save buttons in the change view
+    def change_view(self, request, object_id, form_url='', extra_context=None):
+        extra_context = extra_context or {}
+        extra_context['readonly'] = True
+        return super(ConfigurationModelAdmin, self).change_view(
+            request,
+            object_id,
+            form_url,
+            extra_context=extra_context
+        )
+
+    def save_model(self, request, obj, form, change):
+        obj.changed_by = request.user
+        super(ConfigurationModelAdmin, self).save_model(request, obj, form, change)
+
+    def revert(self, request, queryset):
+        """
+        Admin action to revert a configuration back to the selected value
+        """
+        if queryset.count() != 1:
+            self.message_user(request, "Please select a single configuration to revert to.")
+            return
+
+        target = queryset[0]
+        target.id = None
+        self.save_model(request, target, None, False)
+        self.message_user(request, "Reverted configuration.")
+
+        return HttpResponseRedirect(
+            reverse(
+                'admin:{}_{}_change'.format(
+                    self.model._meta.app_label,
+                    self.model._meta.module_name,
+                ),
+                args=(target.id,),
+            )
+        )
diff --git a/common/djangoapps/config_models/models.py b/common/djangoapps/config_models/models.py
new file mode 100644
index 0000000000..3c1d5d6061
--- /dev/null
+++ b/common/djangoapps/config_models/models.py
@@ -0,0 +1,62 @@
+"""
+Django Model baseclass for database-backed configuration.
+"""
+from django.db import models
+from django.contrib.auth.models import User
+from django.core.cache import get_cache, InvalidCacheBackendError
+
+try:
+    cache = get_cache('configuration')  # pylint: disable=invalid-name
+except InvalidCacheBackendError:
+    from django.core.cache import cache
+
+
+class ConfigurationModel(models.Model):
+    """
+    Abstract base class for model-based configuration
+
+    Properties:
+        cache_timeout (int): The number of seconds that this configuration
+            should be cached
+    """
+
+    class Meta(object):  # pylint: disable=missing-docstring
+        abstract = True
+
+    # The number of seconds
+    cache_timeout = 600
+
+    change_date = models.DateTimeField(auto_now_add=True)
+    changed_by = models.ForeignKey(User, editable=False, null=True, on_delete=models.PROTECT)
+    enabled = models.BooleanField(default=False)
+
+    def save(self, *args, **kwargs):
+        """
+        Clear the cached value when saving a new configuration entry
+        """
+        super(ConfigurationModel, self).save(*args, **kwargs)
+        cache.delete(self.cache_key_name())
+
+    @classmethod
+    def cache_key_name(cls):
+        """Return the name of the key to use to cache the current configuration"""
+        return 'configuration/{}/current'.format(cls.__name__)
+
+    @classmethod
+    def current(cls):
+        """
+        Return the active configuration entry, either from cache,
+        from the database, or by creating a new empty entry (which is not
+        persisted).
+        """
+        cached = cache.get(cls.cache_key_name())
+        if cached is not None:
+            return cached
+
+        try:
+            current = cls.objects.order_by('-change_date')[0]
+        except IndexError:
+            current = cls()
+
+        cache.set(cls.cache_key_name(), current, cls.cache_timeout)
+        return current
diff --git a/common/djangoapps/config_models/templatetags.py b/common/djangoapps/config_models/templatetags.py
new file mode 100644
index 0000000000..8641fd11ea
--- /dev/null
+++ b/common/djangoapps/config_models/templatetags.py
@@ -0,0 +1,29 @@
+"""
+Override the submit_row template tag to remove all save buttons from the
+admin dashboard change view if the context has readonly marked in it.
+"""
+
+from django.contrib.admin.templatetags.admin_modify import register
+from django.contrib.admin.templatetags.admin_modify import submit_row as original_submit_row
+
+
+@register.inclusion_tag('admin/submit_line.html', takes_context=True)
+def submit_row(context):
+    """
+    Overrides 'django.contrib.admin.templatetags.admin_modify.submit_row'.
+
+    Manipulates the context going into that function by hiding all of the buttons
+    in the submit row if the key `readonly` is set in the context.
+    """
+    ctx = original_submit_row(context)
+
+    if context.get('readonly', False):
+        ctx.update({
+            'show_delete_link': False,
+            'show_save_as_new': False,
+            'show_save_and_add_another': False,
+            'show_save_and_continue': False,
+            'show_save': False,
+        })
+    else:
+        return ctx
diff --git a/common/djangoapps/config_models/tests.py b/common/djangoapps/config_models/tests.py
new file mode 100644
index 0000000000..bb14ad18e8
--- /dev/null
+++ b/common/djangoapps/config_models/tests.py
@@ -0,0 +1,76 @@
+"""
+Tests of ConfigurationModel
+"""
+
+from django.contrib.auth.models import User
+from django.db import models
+from django.test import TestCase
+
+from freezegun import freeze_time
+
+from mock import patch
+from config_models.models import ConfigurationModel
+
+
+class ExampleConfig(ConfigurationModel):
+    """
+    Test model for testing ``ConfigurationModels``.
+    """
+    cache_timeout = 300
+
+    string_field = models.TextField()
+    int_field = models.IntegerField(default=10)
+
+
+@patch('config_models.models.cache')
+class ConfigurationModelTests(TestCase):
+    """
+    Tests of ConfigurationModel
+    """
+    def setUp(self):
+        self.user = User()
+        self.user.save()
+
+    def test_cache_deleted_on_save(self, mock_cache):
+        ExampleConfig(changed_by=self.user).save()
+        mock_cache.delete.assert_called_with(ExampleConfig.cache_key_name())
+
+    def test_cache_key_name(self, _mock_cache):
+        self.assertEquals(ExampleConfig.cache_key_name(), 'configuration/ExampleConfig/current')
+
+    def test_no_config_empty_cache(self, mock_cache):
+        mock_cache.get.return_value = None
+
+        current = ExampleConfig.current()
+        self.assertEquals(current.int_field, 10)
+        self.assertEquals(current.string_field, '')
+        mock_cache.set.assert_called_with(ExampleConfig.cache_key_name(), current, 300)
+
+    def test_no_config_full_cache(self, mock_cache):
+        current = ExampleConfig.current()
+        self.assertEquals(current, mock_cache.get.return_value)
+
+    def test_config_ordering(self, mock_cache):
+        mock_cache.get.return_value = None
+
+        with freeze_time('2012-01-01'):
+            first = ExampleConfig(changed_by=self.user)
+            first.string_field = 'first'
+            first.save()
+
+        second = ExampleConfig(changed_by=self.user)
+        second.string_field = 'second'
+        second.save()
+
+        self.assertEquals(ExampleConfig.current().string_field, 'second')
+
+    def test_cache_set(self, mock_cache):
+        mock_cache.get.return_value = None
+
+        first = ExampleConfig(changed_by=self.user)
+        first.string_field = 'first'
+        first.save()
+
+        ExampleConfig.current()
+
+        mock_cache.set.assert_called_with(ExampleConfig.cache_key_name(), first, 300)
diff --git a/common/djangoapps/dark_lang/__init__.py b/common/djangoapps/dark_lang/__init__.py
new file mode 100644
index 0000000000..d56fa38068
--- /dev/null
+++ b/common/djangoapps/dark_lang/__init__.py
@@ -0,0 +1,19 @@
+"""
+Language Translation Dark Launching
+===================================
+
+This app adds the ability to launch language translations that
+are only accessible through the use of a specific query parameter
+(and are not activated by browser settings).
+
+Installation
+------------
+
+Add the ``DarkLangMiddleware`` to your list of ``MIDDLEWARE_CLASSES``.
+It must come after the ``SessionMiddleware``, and before the ``LocaleMiddleware``.
+
+Run migrations to install the configuration table.
+
+Use the admin site to add a new ``DarkLangConfig`` that is enabled, and lists the
+languages that should be released.
+"""
diff --git a/common/djangoapps/dark_lang/admin.py b/common/djangoapps/dark_lang/admin.py
new file mode 100644
index 0000000000..cc80e49b25
--- /dev/null
+++ b/common/djangoapps/dark_lang/admin.py
@@ -0,0 +1,10 @@
+"""
+Admin site bindings for dark_lang
+"""
+
+from django.contrib import admin
+
+from config_models.admin import ConfigurationModelAdmin
+from dark_lang.models import DarkLangConfig
+
+admin.site.register(DarkLangConfig, ConfigurationModelAdmin)
diff --git a/common/djangoapps/dark_lang/middleware.py b/common/djangoapps/dark_lang/middleware.py
new file mode 100644
index 0000000000..88783328be
--- /dev/null
+++ b/common/djangoapps/dark_lang/middleware.py
@@ -0,0 +1,92 @@
+"""
+Middleware for dark-launching languages. These languages won't be used
+when determining which translation to give a user based on their browser
+header, but can be selected by setting the ``preview-lang`` query parameter
+to the language code.
+
+Adding the query parameter ``clear-lang`` will reset the language stored
+in the user's session.
+
+This middleware must be placed before the LocaleMiddleware, but after
+the SessionMiddleware.
+"""
+
+from django.utils.translation.trans_real import parse_accept_lang_header
+
+from dark_lang.models import DarkLangConfig
+
+
+class DarkLangMiddleware(object):
+    """
+    Middleware for dark-launching languages.
+
+    This is configured by creating ``DarkLangConfig`` rows in the database,
+    using the django admin site.
+    """
+
+    @property
+    def released_langs(self):
+        """
+        Current list of released languages
+        """
+        return DarkLangConfig.current().released_languages_list
+
+    def process_request(self, request):
+        """
+        Prevent user from requesting un-released languages except by using the preview-lang query string.
+        """
+        if not DarkLangConfig.current().enabled:
+            return
+
+        self._clean_accept_headers(request)
+        self._activate_preview_language(request)
+
+    def _is_released(self, lang_code):
+        """
+        ``True`` iff one of the values in ``self.released_langs`` is a prefix of ``lang_code``.
+        """
+        return any(lang_code.startswith(released_lang) for released_lang in self.released_langs)
+
+    def _format_accept_value(self, lang, priority=1.0):
+        """
+        Formats lang and priority into a valid accept header fragment.
+        """
+        return "{};q={}".format(lang, priority)
+
+    def _clean_accept_headers(self, request):
+        """
+        Remove any language that is not either in ``self.released_langs`` or
+        a territory of one of those languages.
+        """
+        accept = request.META.get('HTTP_ACCEPT_LANGUAGE', None)
+        if accept is None or accept == '*':
+            return
+
+        new_accept = ", ".join(
+            self._format_accept_value(lang, priority)
+            for lang, priority
+            in parse_accept_lang_header(accept)
+            if self._is_released(lang)
+        )
+
+        request.META['HTTP_ACCEPT_LANGUAGE'] = new_accept
+
+    def _activate_preview_language(self, request):
+        """
+        If the request has the get parameter ``preview-lang``,
+        and that language appears doesn't appear in ``self.released_langs``,
+        then set the session ``django_language`` to that language.
+        """
+        if 'clear-lang' in request.GET:
+            if 'django_language' in request.session:
+                del request.session['django_language']
+
+        preview_lang = request.GET.get('preview-lang', None)
+
+        if not preview_lang:
+            return
+
+        if preview_lang in self.released_langs:
+            return
+
+        request.session['django_language'] = preview_lang
diff --git a/common/djangoapps/dark_lang/migrations/0001_initial.py b/common/djangoapps/dark_lang/migrations/0001_initial.py
new file mode 100644
index 0000000000..cc715fe8e5
--- /dev/null
+++ b/common/djangoapps/dark_lang/migrations/0001_initial.py
@@ -0,0 +1,74 @@
+# -*- coding: utf-8 -*-
+import datetime
+from south.db import db
+from south.v2 import SchemaMigration
+from django.db import models
+
+
+class Migration(SchemaMigration):
+
+    def forwards(self, orm):
+        # Adding model 'DarkLangConfig'
+        db.create_table('dark_lang_darklangconfig', (
+            ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)),
+            ('change_date', self.gf('django.db.models.fields.DateTimeField')(auto_now_add=True, blank=True)),
+            ('changed_by', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['auth.User'], null=True, on_delete=models.PROTECT)),
+            ('enabled', self.gf('django.db.models.fields.BooleanField')(default=False)),
+            ('released_languages', self.gf('django.db.models.fields.TextField')(blank=True)),
+        ))
+        db.send_create_signal('dark_lang', ['DarkLangConfig'])
+
+
+    def backwards(self, orm):
+        # Deleting model 'DarkLangConfig'
+        db.delete_table('dark_lang_darklangconfig')
+
+
+    models = {
+        'auth.group': {
+            'Meta': {'object_name': 'Group'},
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '80'}),
+            'permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'})
+        },
+        'auth.permission': {
+            'Meta': {'ordering': "('content_type__app_label', 'content_type__model', 'codename')", 'unique_together': "(('content_type', 'codename'),)", 'object_name': 'Permission'},
+            'codename': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'content_type': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['contenttypes.ContentType']"}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '50'})
+        },
+        'auth.user': {
+            'Meta': {'object_name': 'User'},
+            'date_joined': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'email': ('django.db.models.fields.EmailField', [], {'max_length': '75', 'blank': 'True'}),
+            'first_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'groups': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Group']", 'symmetrical': 'False', 'blank': 'True'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'is_active': ('django.db.models.fields.BooleanField', [], {'default': 'True'}),
+            'is_staff': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'is_superuser': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'last_login': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'last_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'password': ('django.db.models.fields.CharField', [], {'max_length': '128'}),
+            'user_permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'}),
+            'username': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '30'})
+        },
+        'contenttypes.contenttype': {
+            'Meta': {'ordering': "('name',)", 'unique_together': "(('app_label', 'model'),)", 'object_name': 'ContentType', 'db_table': "'django_content_type'"},
+            'app_label': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'model': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '100'})
+        },
+        'dark_lang.darklangconfig': {
+            'Meta': {'object_name': 'DarkLangConfig'},
+            'change_date': ('django.db.models.fields.DateTimeField', [], {'auto_now_add': 'True', 'blank': 'True'}),
+            'changed_by': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['auth.User']", 'null': 'True', 'on_delete': 'models.PROTECT'}),
+            'enabled': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'released_languages': ('django.db.models.fields.TextField', [], {'blank': 'True'})
+        }
+    }
+
+    complete_apps = ['dark_lang']
\ No newline at end of file
diff --git a/common/djangoapps/dark_lang/migrations/0002_enable_on_install.py b/common/djangoapps/dark_lang/migrations/0002_enable_on_install.py
new file mode 100644
index 0000000000..c794a156ce
--- /dev/null
+++ b/common/djangoapps/dark_lang/migrations/0002_enable_on_install.py
@@ -0,0 +1,68 @@
+# -*- coding: utf-8 -*-
+import datetime
+from south.db import db
+from south.v2 import DataMigration
+from django.db import models
+
+class Migration(DataMigration):
+
+    def forwards(self, orm):
+        """
+        Enable DarkLang by default when it is installed, to prevent accidental
+        release of testing languages.
+        """
+        orm.DarkLangConfig(enabled=True).save()
+
+    def backwards(self, orm):
+        "Write your backwards methods here."
+        raise RuntimeError("Cannot reverse this migration.")
+
+    models = {
+        'auth.group': {
+            'Meta': {'object_name': 'Group'},
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '80'}),
+            'permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'})
+        },
+        'auth.permission': {
+            'Meta': {'ordering': "('content_type__app_label', 'content_type__model', 'codename')", 'unique_together': "(('content_type', 'codename'),)", 'object_name': 'Permission'},
+            'codename': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'content_type': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['contenttypes.ContentType']"}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '50'})
+        },
+        'auth.user': {
+            'Meta': {'object_name': 'User'},
+            'date_joined': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'email': ('django.db.models.fields.EmailField', [], {'max_length': '75', 'blank': 'True'}),
+            'first_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'groups': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Group']", 'symmetrical': 'False', 'blank': 'True'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'is_active': ('django.db.models.fields.BooleanField', [], {'default': 'True'}),
+            'is_staff': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'is_superuser': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'last_login': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'last_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'password': ('django.db.models.fields.CharField', [], {'max_length': '128'}),
+            'user_permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'}),
+            'username': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '30'})
+        },
+        'contenttypes.contenttype': {
+            'Meta': {'ordering': "('name',)", 'unique_together': "(('app_label', 'model'),)", 'object_name': 'ContentType', 'db_table': "'django_content_type'"},
+            'app_label': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'model': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '100'})
+        },
+        'dark_lang.darklangconfig': {
+            'Meta': {'object_name': 'DarkLangConfig'},
+            'change_date': ('django.db.models.fields.DateTimeField', [], {'auto_now_add': 'True', 'blank': 'True'}),
+            'changed_by': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['auth.User']", 'null': 'True', 'on_delete': 'models.PROTECT'}),
+            'enabled': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'released_languages': ('django.db.models.fields.TextField', [], {'blank': 'True'})
+        }
+    }
+
+    complete_apps = ['dark_lang']
+    symmetrical = True
diff --git a/common/djangoapps/dark_lang/migrations/__init__.py b/common/djangoapps/dark_lang/migrations/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/common/djangoapps/dark_lang/models.py b/common/djangoapps/dark_lang/models.py
new file mode 100644
index 0000000000..9912287b4e
--- /dev/null
+++ b/common/djangoapps/dark_lang/models.py
@@ -0,0 +1,26 @@
+"""
+Models for the dark-launching languages
+"""
+from django.db import models
+
+from config_models.models import ConfigurationModel
+
+
+class DarkLangConfig(ConfigurationModel):
+    """
+    Configuration for the dark_lang django app
+    """
+    released_languages = models.TextField(
+        blank=True,
+        help_text="A comma-separated list of language codes to release to the public."
+    )
+
+    @property
+    def released_languages_list(self):
+        """
+        ``released_languages`` as a list of language codes.
+        """
+        if not self.released_languages.strip():  # pylint: disable=no-member
+            return []
+
+        return [lang.strip() for lang in self.released_languages.split(',')]  # pylint: disable=no-member
diff --git a/common/djangoapps/dark_lang/tests.py b/common/djangoapps/dark_lang/tests.py
new file mode 100644
index 0000000000..7667102b90
--- /dev/null
+++ b/common/djangoapps/dark_lang/tests.py
@@ -0,0 +1,193 @@
+"""
+Tests of DarkLangMiddleware
+"""
+
+from django.contrib.auth.models import User
+from django.http import HttpRequest
+
+from django.test import TestCase
+from mock import Mock
+
+from dark_lang.middleware import DarkLangMiddleware
+from dark_lang.models import DarkLangConfig
+
+
+UNSET = object()
+
+
+def set_if_set(dct, key, value):
+    """
+    Sets ``key`` in ``dct`` to ``value``
+    unless ``value`` is ``UNSET``
+    """
+    if value is not UNSET:
+        dct[key] = value
+
+
+class DarkLangMiddlewareTests(TestCase):
+    """
+    Tests of DarkLangMiddleware
+    """
+    def setUp(self):
+        self.user = User()
+        self.user.save()
+        DarkLangConfig(
+            released_languages='rel',
+            changed_by=self.user,
+            enabled=True
+        ).save()
+
+    def process_request(self, django_language=UNSET, accept=UNSET, preview_lang=UNSET, clear_lang=UNSET):
+        """
+        Build a request and then process it using the ``DarkLangMiddleware``.
+
+        Args:
+            django_language (str): The language code to set in request.session['django_language']
+            accept (str): The accept header to set in request.META['HTTP_ACCEPT_LANGUAGE']
+            preview_lang (str): The value to set in request.GET['preview_lang']
+            clear_lang (str): The value to set in request.GET['clear_lang']
+        """
+        session = {}
+        set_if_set(session, 'django_language', django_language)
+
+        meta = {}
+        set_if_set(meta, 'HTTP_ACCEPT_LANGUAGE', accept)
+
+        get = {}
+        set_if_set(get, 'preview-lang', preview_lang)
+        set_if_set(get, 'clear-lang', clear_lang)
+
+        request = Mock(
+            spec=HttpRequest,
+            session=session,
+            META=meta,
+            GET=get
+        )
+        self.assertIsNone(DarkLangMiddleware().process_request(request))
+        return request
+
+    def assertAcceptEquals(self, value, request):
+        """
+        Assert that the HTML_ACCEPT_LANGUAGE header in request
+        is equal to value
+        """
+        self.assertEquals(
+            value,
+            request.META.get('HTTP_ACCEPT_LANGUAGE', UNSET)
+        )
+
+    def test_empty_accept(self):
+        self.assertAcceptEquals(UNSET, self.process_request())
+
+    def test_wildcard_accept(self):
+        self.assertAcceptEquals('*', self.process_request(accept='*'))
+
+    def test_released_accept(self):
+        self.assertAcceptEquals(
+            'rel;q=1.0',
+            self.process_request(accept='rel;q=1.0')
+        )
+
+    def test_unreleased_accept(self):
+        self.assertAcceptEquals(
+            'rel;q=1.0',
+            self.process_request(accept='rel;q=1.0, unrel;q=0.5')
+        )
+
+    def test_accept_multiple_released_langs(self):
+        DarkLangConfig(
+            released_languages=('rel, unrel'),
+            changed_by=self.user,
+            enabled=True
+        ).save()
+
+        self.assertAcceptEquals(
+            'rel;q=1.0, unrel;q=0.5',
+            self.process_request(accept='rel;q=1.0, unrel;q=0.5')
+        )
+
+        self.assertAcceptEquals(
+            'rel;q=1.0, unrel;q=0.5',
+            self.process_request(accept='rel;q=1.0, notrel;q=0.3, unrel;q=0.5')
+        )
+
+        self.assertAcceptEquals(
+            'rel;q=1.0, unrel;q=0.5',
+            self.process_request(accept='notrel;q=0.3, rel;q=1.0, unrel;q=0.5')
+        )
+
+    def test_accept_released_territory(self):
+        self.assertAcceptEquals(
+            'rel-ter;q=1.0, rel;q=0.5',
+            self.process_request(accept='rel-ter;q=1.0, rel;q=0.5')
+        )
+
+    def assertSessionLangEquals(self, value, request):
+        """
+        Assert that the 'django_language' set in request.session is equal to value
+        """
+        self.assertEquals(
+            value,
+            request.session.get('django_language', UNSET)
+        )
+
+    def test_preview_lang_with_released_language(self):
+        self.assertSessionLangEquals(
+            UNSET,
+            self.process_request(preview_lang='rel')
+        )
+
+        self.assertSessionLangEquals(
+            'notrel',
+            self.process_request(preview_lang='rel', django_language='notrel')
+        )
+
+    def test_preview_lang_with_dark_language(self):
+        self.assertSessionLangEquals(
+            'unrel',
+            self.process_request(preview_lang='unrel')
+        )
+
+        self.assertSessionLangEquals(
+            'unrel',
+            self.process_request(preview_lang='unrel', django_language='notrel')
+        )
+
+    def test_clear_lang(self):
+        self.assertSessionLangEquals(
+            UNSET,
+            self.process_request(clear_lang=True)
+        )
+
+        self.assertSessionLangEquals(
+            UNSET,
+            self.process_request(clear_lang=True, django_language='rel')
+        )
+
+        self.assertSessionLangEquals(
+            UNSET,
+            self.process_request(clear_lang=True, django_language='unrel')
+        )
+
+    def test_disabled(self):
+        DarkLangConfig(enabled=False, changed_by=self.user).save()
+
+        self.assertAcceptEquals(
+            'notrel;q=0.3, rel;q=1.0, unrel;q=0.5',
+            self.process_request(accept='notrel;q=0.3, rel;q=1.0, unrel;q=0.5')
+        )
+
+        self.assertSessionLangEquals(
+            'rel',
+            self.process_request(clear_lang=True, django_language='rel')
+        )
+
+        self.assertSessionLangEquals(
+            'unrel',
+            self.process_request(clear_lang=True, django_language='unrel')
+        )
+
+        self.assertSessionLangEquals(
+            'rel',
+            self.process_request(preview_lang='unrel', django_language='rel')
+        )
diff --git a/lms/envs/common.py b/lms/envs/common.py
index 68b4d8b18b..5bf9268388 100644
--- a/lms/envs/common.py
+++ b/lms/envs/common.py
@@ -492,14 +492,12 @@ FAVICON_PATH = 'images/favicon.ico'
 # Locale/Internationalization
 TIME_ZONE = 'America/New_York'  # http://en.wikipedia.org/wiki/List_of_tz_zones_by_name
 LANGUAGE_CODE = 'en'  # http://www.i18nguy.com/unicode/language-identifiers.html
-LANGUAGES = ()
 
-# We want i18n to be turned off in production, at least until we have full localizations.
-# Thus we want the Django translation engine to be disabled. Otherwise even without
-# localization files, if the user's browser is set to a language other than us-en,
-# strings like "login" and "password" will be translated and the rest of the page will be
-# in English, which is confusing.
-USE_I18N = False
+LANGUAGES = (
+    ('eo', 'Esperanto'),
+)
+
+USE_I18N = True
 USE_L10N = True
 
 # Localization strings (e.g. django.po) are under this directory
@@ -639,6 +637,9 @@ MIDDLEWARE_CLASSES = (
 
     'course_wiki.course_nav.Middleware',
 
+    # Allows us to dark-launch particular languages
+    'dark_lang.middleware.DarkLangMiddleware',
+
     # Detects user-requested locale from 'accept-language' header in http request
     'django.middleware.locale.LocaleMiddleware',
 
@@ -977,6 +978,9 @@ INSTALLED_APPS = (
     'djcelery',
     'south',
 
+    # Database-backed configuration
+    'config_models',
+
     # Monitor the status of services
     'service_status',
 
@@ -1055,6 +1059,9 @@ INSTALLED_APPS = (
 
     # Student Identity Verification
     'verify_student',
+
+    # Dark-launching languages
+    'dark_lang',
 )
 
 ######################### MARKETING SITE ###############################
diff --git a/lms/envs/dev.py b/lms/envs/dev.py
index 8f40887433..fc486726bf 100644
--- a/lms/envs/dev.py
+++ b/lms/envs/dev.py
@@ -16,11 +16,6 @@ from .common import *
 from logsettings import get_logger_config
 
 DEBUG = True
-USE_I18N = True
-# For displaying the dummy text, we need to provide a language mapping.
-LANGUAGES = (
-    ('eo', 'Esperanto'),
-)
 TEMPLATE_DEBUG = True
 
 FEATURES['DISABLE_START_DATES'] = False
diff --git a/rakelib/tests.rake b/rakelib/tests.rake
index 868fa5836f..e09c5d0762 100644
--- a/rakelib/tests.rake
+++ b/rakelib/tests.rake
@@ -22,10 +22,15 @@ def run_tests(system, report_dir, test_id=nil, stop_on_failure=true)
     # to the Djangoapps we want to test.  Otherwise, it will
     # run tests on all installed packages.
 
-    default_test_id = "#{system}/djangoapps common/djangoapps"
+    # We need to use $DIR/*, rather than just $DIR so that
+    # django-nose will import them early in the test process,
+    # thereby making sure that we load any django models that are
+    # only defined in test files.
+
+    default_test_id = "#{system}/djangoapps/* common/djangoapps/*"
 
     if system == :lms || system == :cms
-        default_test_id += " #{system}/lib"
+        default_test_id += " #{system}/lib/*"
     end
 
     if test_id.nil?
diff --git a/requirements/edx/base.txt b/requirements/edx/base.txt
index bce6479748..3df9a7034a 100644
--- a/requirements/edx/base.txt
+++ b/requirements/edx/base.txt
@@ -94,21 +94,22 @@ transifex-client==0.10
 # Used for testing
 coverage==3.7
 ddt==0.6.0
+django-crum==0.5
+django-debug-toolbar-mongo
+django_debug_toolbar==0.9.4
+django_nose==1.1
 factory_boy==2.2.1
+freezegun==0.1.11
 mock==1.0.1
+nose-exclude
+nose-ignore-docstring
 nosexcover==1.0.7
 pep8==1.4.5
 pylint==0.28
+python-subunit==0.0.16
 rednose==0.3
 selenium==2.34.0
 splinter==0.5.4
-django_nose==1.1
-django_debug_toolbar==0.9.4
-django-debug-toolbar-mongo
-nose-ignore-docstring
-nose-exclude
-django-crum==0.5
-python-subunit==0.0.16
 testtools==0.9.34
 
 git+https://github.com/mfogel/django-settings-context-processor.git