diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigStorageController.php b/core/lib/Drupal/Core/Config/Entity/ConfigStorageController.php
index dd4c028a6b58faa08c0d0146a24570c2da6a1835..5487e04d0a62c54437a057bbe11b98773feab40d 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigStorageController.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigStorageController.php
@@ -284,6 +284,9 @@ protected function attachLoad(&$queried_entities, $revision_id = FALSE) {
   public function create(array $values) {
     $class = $this->entityInfo['class'];
 
+    // Set default language to site default if not provided.
+    $values += array('langcode' => language_default()->langcode);
+
     $entity = new $class($values, $this->entityType);
     // Mark this entity as new, so isNew() returns TRUE. This does not check
     // whether a configuration entity with the same ID (if any) already exists.
diff --git a/core/lib/Drupal/Core/Entity/EntityFormController.php b/core/lib/Drupal/Core/Entity/EntityFormController.php
index 4a03975c2c509f3dba7f4e46c61aeb92df262b0a..6d2c9fb8ca343b40fcf5ae71663b6b21381ac61d 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormController.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormController.php
@@ -80,6 +80,15 @@ public function form(array $form, array &$form_state, EntityInterface $entity) {
     if (!empty($info['fieldable'])) {
       field_attach_form($entity, $form, $form_state, $this->getFormLangcode($form_state));
     }
+    if (!isset($form['langcode'])) {
+      // If the form did not specify otherwise, default to keeping the existing
+      // language of the entity or defaulting to the site default language for
+      // new entities.
+      $form['langcode'] = array(
+        '#type' => 'value',
+        '#value' => !$entity->isNew() ? $entity->langcode : language_default()->langcode,
+      );
+    }
     return $form;
   }
 
diff --git a/core/modules/block/custom_block/config/custom_block.type.basic.yml b/core/modules/block/custom_block/config/custom_block.type.basic.yml
index 1b0e2f8dc5341bf92b06675112dd20bace46e673..58e87d757bcdfdd533481da19b98ba0abc0eacb5 100644
--- a/core/modules/block/custom_block/config/custom_block.type.basic.yml
+++ b/core/modules/block/custom_block/config/custom_block.type.basic.yml
@@ -2,3 +2,4 @@ id: basic
 label: Basic block
 revision: '0'
 description: A basic block contains a title and a body.
+langcode: en
diff --git a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockTypeTest.php b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockTypeTest.php
index d94e47638cd96b5d75be8705d05f04cac49eddac..eee184adbb16a45421fbb9fb5ca9b599f26df181 100644
--- a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockTypeTest.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockTypeTest.php
@@ -64,6 +64,10 @@ public function testCustomBlockTypeCreation() {
     $this->drupalPost('admin/structure/custom-blocks/add', $edit, t('Save'));
     $block_type = entity_load('custom_block_type', 'foo');
     $this->assertTrue($block_type, 'The new block type has been created.');
+
+    // Check that the block type was created in site default language.
+    $default_langcode = language_default()->langcode;
+    $this->assertEqual($block_type->langcode, $default_langcode);
   }
 
   /**
diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockStorageUnitTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockStorageUnitTest.php
index 490e434fa8295a22443a32b6920fb9fc50c21459..207f20bd001f5325dacb771264d6dab77ac8c407 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockStorageUnitTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockStorageUnitTest.php
@@ -104,7 +104,7 @@ protected function createTests() {
         'cache' => '1',
         'admin_label' => t('Test block html id'),
       ),
-      'langcode' => LANGUAGE_NOT_SPECIFIED,
+      'langcode' => language_default()->langcode,
     );
     $this->assertIdentical($actual_properties, $expected_properties, 'The block properties are exported correctly.');
 
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php
index 90ae934d33c1f33d70b6d75dc35ea57a3765b11f..84fbc97b82302a169bb0b51208551b32420370c7 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigEntityTest.php
@@ -35,13 +35,14 @@ public static function getInfo() {
    */
   function testCRUD() {
     $manifest_name = 'manifest.config_test.dynamic';
+    $default_langcode = language_default()->langcode;
     // Verify default properties on a newly created empty entity.
     $empty = entity_create('config_test', array());
     $this->assertIdentical($empty->id, NULL);
     $this->assertTrue($empty->uuid);
     $this->assertIdentical($empty->label, NULL);
     $this->assertIdentical($empty->style, NULL);
-    $this->assertIdentical($empty->langcode, LANGUAGE_NOT_SPECIFIED);
+    $this->assertIdentical($empty->langcode, $default_langcode);
 
     // Verify ConfigEntity properties/methods on the newly created empty entity.
     $this->assertIdentical($empty->isNew(), TRUE);
@@ -55,7 +56,7 @@ function testCRUD() {
     $this->assertTrue($empty->get('uuid'));
     $this->assertIdentical($empty->get('label'), NULL);
     $this->assertIdentical($empty->get('style'), NULL);
-    $this->assertIdentical($empty->get('langcode'), LANGUAGE_NOT_SPECIFIED);
+    $this->assertIdentical($empty->get('langcode'), $default_langcode);
 
     // Verify Entity properties/methods on the newly created empty entity.
     $this->assertIdentical($empty->isNewRevision(), FALSE);
@@ -97,7 +98,7 @@ function testCRUD() {
     $this->assertNotEqual($config_test->uuid, $empty->uuid);
     $this->assertIdentical($config_test->label, $expected['label']);
     $this->assertIdentical($config_test->style, $expected['style']);
-    $this->assertIdentical($config_test->langcode, LANGUAGE_NOT_SPECIFIED);
+    $this->assertIdentical($config_test->langcode, $default_langcode);
 
     // Verify methods on the newly created entity.
     $this->assertIdentical($config_test->isNew(), TRUE);
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImportTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImportTest.php
index 9278269d10db035064942ce922961add6c363999..03fda2a77c70f693173364c067ca4c5f7fa4391a 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImportTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImportTest.php
@@ -110,7 +110,7 @@ function testNew() {
       'label' => 'New',
       'style' => '',
       'status' => '1',
-      'langcode' => 'und',
+      'langcode' => language_default()->langcode,
       'protected_property' => '',
     );
     $staging->write($dynamic_name, $original_dynamic_data);
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
index 3788d67c92b31fc3121e7b0cf65ef225cab41254..cf87bb396559cbdb523e31fec12bf4a85658873a 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
@@ -61,7 +61,7 @@ function testImport() {
       'label' => 'New',
       'style' => '',
       'status' => '1',
-      'langcode' => 'und',
+      'langcode' => language_default()->langcode,
       'protected_property' => '',
     );
     $staging->write($dynamic_name, $original_dynamic_data);
diff --git a/core/modules/contact/config/contact.category.feedback.yml b/core/modules/contact/config/contact.category.feedback.yml
index 8aff8c61c25fb35d3a592056131d5737c7e46b0b..aae9098cb2b4826f05f2bff0beb66f2c460f620a 100644
--- a/core/modules/contact/config/contact.category.feedback.yml
+++ b/core/modules/contact/config/contact.category.feedback.yml
@@ -3,3 +3,4 @@ label: 'Website feedback'
 recipients: []
 reply: ''
 weight: '0'
+langcode: en
diff --git a/core/modules/contact/lib/Drupal/contact/Tests/ContactSitewideTest.php b/core/modules/contact/lib/Drupal/contact/Tests/ContactSitewideTest.php
index bdc98efe9b4c7b76d45a741bf191e6f3fd52b01c..1ea830b49a4e2ab67cd88840573e198dd9d8166f 100644
--- a/core/modules/contact/lib/Drupal/contact/Tests/ContactSitewideTest.php
+++ b/core/modules/contact/lib/Drupal/contact/Tests/ContactSitewideTest.php
@@ -82,6 +82,11 @@ function testSiteWideContact() {
     $this->addCategory($id = drupal_strtolower($this->randomName(16)), $label = $this->randomName(16), implode(',', array($recipients[0])), '', TRUE);
     $this->assertRaw(t('Category %label has been added.', array('%label' => $label)));
 
+    // Check that the category was created in site default language.
+    $langcode = config('contact.category.' . $id)->get('langcode');
+    $default_langcode = language_default()->langcode;
+    $this->assertEqual($langcode, $default_langcode);
+
     // Make sure the newly created category is included in the list of categories.
     $this->assertNoUniqueText($label, 'New category included in categories list.');
 
diff --git a/core/modules/filter/filter.admin.inc b/core/modules/filter/filter.admin.inc
index e78ce67dacc03a9caf6201810330f1581a9a2abe..aa3018cf175cf317b871e0b5dcaf3637102ff59b 100644
--- a/core/modules/filter/filter.admin.inc
+++ b/core/modules/filter/filter.admin.inc
@@ -169,6 +169,11 @@ function filter_admin_format_form($form, &$form_state, $format) {
     '#disabled' => !empty($format->format),
     '#weight' => -20,
   );
+  // @todo Remove once moved to FilterFormatFormController.
+  $form['langcode'] = array(
+    '#type' => 'value',
+    '#value' => !$format->isNew() ? $format->langcode : language_default()->langcode,
+  );
 
   // Add user role access selection.
   $form['roles'] = array(
diff --git a/core/modules/filter/lib/Drupal/filter/Tests/FilterCrudTest.php b/core/modules/filter/lib/Drupal/filter/Tests/FilterCrudTest.php
index 21dcbf091ec4dd2b50292561dd41f88f89ec1308..7ba7b7da5c569649bf88256d27fa49f4333094d3 100644
--- a/core/modules/filter/lib/Drupal/filter/Tests/FilterCrudTest.php
+++ b/core/modules/filter/lib/Drupal/filter/Tests/FilterCrudTest.php
@@ -84,6 +84,7 @@ function testTextFormatCrud() {
    */
   function verifyTextFormat($format) {
     $t_args = array('%format' => $format->name);
+    $default_langcode = language_default()->langcode;
 
     // Verify filter_format_load().
     $filter_format = filter_format_load($format->format);
@@ -91,6 +92,8 @@ function verifyTextFormat($format) {
     $this->assertEqual($filter_format->name, $format->name, format_string('filter_format_load: Proper title for text format %format.', $t_args));
     $this->assertEqual($filter_format->cache, $format->cache, format_string('filter_format_load: Proper cache indicator for text format %format.', $t_args));
     $this->assertEqual($filter_format->weight, $format->weight, format_string('filter_format_load: Proper weight for text format %format.', $t_args));
+    // Check that the filter was created in site default language.
+    $this->assertEqual($format->langcode, $default_langcode, format_string('filter_format_load: Proper language code for text format %format.', $t_args));
 
     // Verify the 'cache' text format property according to enabled filters.
     $filter_info = filter_get_filters();
diff --git a/core/modules/user/config/user.role.anonymous.yml b/core/modules/user/config/user.role.anonymous.yml
index 11defb06f09318cb56c9099bd3eeb022d5367abf..1947f35310c379be5049ec8211d1db851ddd644e 100644
--- a/core/modules/user/config/user.role.anonymous.yml
+++ b/core/modules/user/config/user.role.anonymous.yml
@@ -1,3 +1,4 @@
 id: anonymous
 label: Anonymous user
 weight: 0
+langcode: en
diff --git a/core/modules/user/config/user.role.authenticated.yml b/core/modules/user/config/user.role.authenticated.yml
index dc4b65d6311d2b30dabb179d132612636fa7b4df..16df96d3c981c70dac4506b0b44b1fb829e977ec 100644
--- a/core/modules/user/config/user.role.authenticated.yml
+++ b/core/modules/user/config/user.role.authenticated.yml
@@ -1,3 +1,4 @@
 id: authenticated
 label: Authenticated user
 weight: 1
+langcode: en
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserRoleAdminTest.php b/core/modules/user/lib/Drupal/user/Tests/UserRoleAdminTest.php
index d322a640743177e4d04d0f41fce01b2fe7d6ec1b..0025873d169bfd376127c2795e0abe4576e16a5e 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserRoleAdminTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserRoleAdminTest.php
@@ -32,6 +32,7 @@ function setUp() {
    */
   function testRoleAdministration() {
     $this->drupalLogin($this->admin_user);
+    $default_langcode = language_default()->langcode;
 
     // Test adding a role. (In doing so, we use a role name that happens to
     // correspond to an integer, to test that the role administration pages
@@ -43,6 +44,9 @@ function testRoleAdministration() {
     $role = entity_load('user_role', $role_name);
     $this->assertTrue(is_object($role), 'The role was successfully retrieved from the database.');
 
+    // Check that the role was created in site default language.
+    $this->assertEqual($role->langcode, $default_langcode);
+
     // Try adding a duplicate role.
     $this->drupalPost(NULL, $edit, t('Add role'));
     $this->assertRaw(t('The machine-readable name is already in use. It must be unique.'), 'Duplicate role warning displayed.');
diff --git a/core/modules/user/user.admin.inc b/core/modules/user/user.admin.inc
index c3931d8490d449a38951730241283155090502e0..882cef2dd1bfe3c9748e274e79674201e2652dd0 100644
--- a/core/modules/user/user.admin.inc
+++ b/core/modules/user/user.admin.inc
@@ -1004,6 +1004,11 @@ function user_admin_role($form, $form_state, $role) {
       'source' => array('role', 'label'),
     ),
   );
+  // @todo Remove once moved to RoleFormController.
+  $form['role']['langcode'] = array(
+    '#type' => 'value',
+    '#value' => !$role->isNew() ? $role->langcode : language_default()->langcode,
+  );
   $form['role']['weight'] = array(
     '#type' => 'value',
     '#value' => $role->weight,