diff --git a/core/config/core.extension.yml b/core/config/core.extension.yml
new file mode 100644
index 0000000..1514a9e
--- /dev/null
+++ b/core/config/core.extension.yml
@@ -0,0 +1,4 @@
+module: {}
+theme: {}
+disabled:
+  theme: {}
diff --git a/core/lib/Drupal/Core/Config/Schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
similarity index 100%
rename from core/lib/Drupal/Core/Config/Schema/core.data_types.schema.yml
rename to core/config/schema/core.data_types.schema.yml
diff --git a/core/config/schema/core.extension.schema.yml b/core/config/schema/core.extension.schema.yml
new file mode 100644
index 0000000..3b93d92
--- /dev/null
+++ b/core/config/schema/core.extension.schema.yml
@@ -0,0 +1,26 @@
+core.extension:
+  type: mapping
+  label: 'Extension settings'
+  mapping:
+    module:
+      type: sequence
+      label: 'Enabled modules'
+      sequence:
+        - type: integer
+          label: 'Weight'
+    theme:
+      type: sequence
+      label: 'Enabled themes'
+      sequence:
+        - type: integer
+          label: 'Weight'
+    disabled:
+      type: mapping
+      label: 'Disabled extensions'
+      mapping:
+        theme:
+          type: sequence
+          label: 'Disabled themes'
+          sequence:
+            - type: integer
+              label: 'Weight'
diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index a704ebf..0404dca 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -575,6 +575,10 @@ function drupal_get_filename($type, $name, $filename = NULL) {
   // drupal_static().
   static $files = array();
 
+  if ($type === 'core') {
+    return 'core/core.info.yml';
+  }
+
   // Profiles are converted into modules in system_rebuild_module_data().
   // @todo Remove false-exposure of profiles as modules.
   $original_type = $type;
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index d335e65..38d09dc 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -954,6 +954,9 @@ function install_verify_requirements(&$install_state) {
  *   An array of information about the current installation state.
  */
 function install_base_system(&$install_state) {
+  // Install base system configuration.
+  \Drupal::service('config.installer')->installDefaultConfig('core', 'core');
+
   // Install system.module.
   drupal_install_system($install_state);
 
diff --git a/core/includes/install.inc b/core/includes/install.inc
index 6f61503..d080733 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -627,9 +627,6 @@ function drupal_verify_profile($install_state) {
  *   to set the default language.
  */
 function drupal_install_system($install_state) {
-  // Create tables.
-  drupal_install_schema('system');
-
   // Immediately boot a new kernel into the regular production environment.
   $request = \Drupal::hasRequest() ? \Drupal::request() : FALSE;
 
@@ -642,32 +639,7 @@ function drupal_install_system($install_state) {
     $kernel->getContainer()->set('request', $request, 'request');
   }
 
-  $system_path = drupal_get_path('module', 'system');
-  require_once DRUPAL_ROOT . '/' . $system_path . '/system.install';
-
-  // Set the schema version to the number of the last update provided by the
-  // module, or the minimum core schema version.
-  $system_version = \Drupal::CORE_MINIMUM_SCHEMA_VERSION;
-  $system_versions = drupal_get_schema_versions('system');
-  if ($system_versions) {
-    $system_version = max(max($system_versions), $system_version);
-  }
-  \Drupal::keyValue('system.schema')->set('system', $system_version);
-
-  // System module needs to be enabled and the system/module lists need to be
-  // reset first in order to allow installation of default configuration to
-  // invoke config import callbacks.
-  // @todo Installation profiles may override the system.module config object.
-  \Drupal::config('system.module')
-    ->set('enabled.system', 0)
-    ->save();
-
-  // Update the module list to include it. Reboot the kernel too.
-  \Drupal::moduleHandler()->addModule('system', 'core/modules/system');
-  $module_list = \Drupal::moduleHandler()->getModuleList();
-  $kernel->updateModules($module_list);
-
-  \Drupal::service('config.installer')->installDefaultConfig('module', 'system');
+  \Drupal::moduleHandler()->install(array('system'), FALSE);
 
   // Ensure default language is saved.
   if (isset($install_state['parameters']['langcode'])) {
@@ -675,8 +647,6 @@ function drupal_install_system($install_state) {
       ->set('langcode', $install_state['parameters']['langcode'])
       ->save();
   }
-
-  \Drupal::moduleHandler()->invoke('system', 'install');
 }
 
 /**
diff --git a/core/includes/module.inc b/core/includes/module.inc
index 7bb0e3e..7e6339a 100644
--- a/core/includes/module.inc
+++ b/core/includes/module.inc
@@ -41,7 +41,7 @@ function system_list($type) {
       'filepaths' => array(),
     );
     // Build a list of themes.
-    $enabled_themes = (array) \Drupal::config('system.theme')->get('enabled');
+    $enabled_themes = (array) \Drupal::config('core.extension')->get('theme');
     // @todo Themes include all themes, including disabled/uninstalled. This
     //   system.theme.data state will go away entirely as soon as themes have
     //   a proper installation status.
@@ -305,11 +305,11 @@ function drupal_required_modules() {
  */
 function module_set_weight($module, $weight) {
   // Update the module weight in the config file that contains it.
-  $module_config = \Drupal::config('system.module');
-  if ($module_config->get("enabled.$module") !== NULL) {
+  $module_config = \Drupal::config('core.extension');
+  if ($module_config->get("module.$module") !== NULL) {
     $module_config
-      ->set("enabled.$module", $weight)
-      ->set('enabled', module_config_sort($module_config->get('enabled')))
+      ->set("module.$module", $weight)
+      ->set('module', module_config_sort($module_config->get('module')))
       ->save();
 
     // Prepare the new module list, sorted by weight, including filenames.
@@ -317,7 +317,7 @@ function module_set_weight($module, $weight) {
     $module_handler = \Drupal::moduleHandler();
     $current_module_filenames = $module_handler->getModuleList();
     $current_modules = array_fill_keys(array_keys($current_module_filenames), 0);
-    $current_modules = module_config_sort(array_merge($current_modules, $module_config->get('enabled')));
+    $current_modules = module_config_sort(array_merge($current_modules, $module_config->get('module')));
     $module_filenames = array();
     foreach ($current_modules as $name => $weight) {
       $module_filenames[$name] = $current_module_filenames[$name];
diff --git a/core/lib/Drupal/Core/Config/ConfigInstaller.php b/core/lib/Drupal/Core/Config/ConfigInstaller.php
index 3769a7b..02fe605 100644
--- a/core/lib/Drupal/Core/Config/ConfigInstaller.php
+++ b/core/lib/Drupal/Core/Config/ConfigInstaller.php
@@ -94,8 +94,11 @@ public function installDefaultConfig($type, $name) {
 
       // Read enabled extensions directly from configuration to avoid circular
       // dependencies with ModuleHandler and ThemeHandler.
-      $enabled_extensions = array_keys((array) $this->configFactory->get('system.module')->get('enabled'));
-      $enabled_extensions += array_keys((array) $this->configFactory->get('system.theme')->get('enabled'));
+      $enabled_extensions = array();
+      if ($type !== 'core') {
+        $enabled_extensions += array_keys((array) $this->configFactory->get('core.extension')->get('module'));
+        $enabled_extensions += array_keys((array) $this->configFactory->get('core.extension')->get('theme'));
+      }
 
       $other_module_config = array_filter($other_module_config, function ($config_name) use ($enabled_extensions) {
         $provider = Unicode::substr($config_name, 0, strpos($config_name, '.'));
diff --git a/core/lib/Drupal/Core/Config/ExtensionInstallStorage.php b/core/lib/Drupal/Core/Config/ExtensionInstallStorage.php
index 60f4188..efaef95 100644
--- a/core/lib/Drupal/Core/Config/ExtensionInstallStorage.php
+++ b/core/lib/Drupal/Core/Config/ExtensionInstallStorage.php
@@ -55,13 +55,14 @@ public function reset() {
   protected function getAllFolders() {
     if (!isset($this->folders)) {
       $this->folders = array();
-      $modules = $this->configStorage->read('system.module');
-      if (isset($modules['enabled'])) {
-        $this->folders += $this->getComponentNames('module', array_keys($modules['enabled']));
+      $this->folders += $this->getComponentNames('core', array('core'));
+
+      $extensions = $this->configStorage->read('core.extension');
+      if (!empty($extensions['module'])) {
+        $this->folders += $this->getComponentNames('module', array_keys($extensions['module']));
       }
-      $themes = $this->configStorage->read('system.theme');
-      if (isset($themes['enabled'])) {
-        $this->folders += $this->getComponentNames('theme', array_keys($themes['enabled']));
+      if (!empty($extensions['theme'])) {
+        $this->folders += $this->getComponentNames('theme', array_keys($extensions['theme']));
       }
 
       // The install profile can override module default configuration. We do
diff --git a/core/lib/Drupal/Core/Config/InstallStorage.php b/core/lib/Drupal/Core/Config/InstallStorage.php
index eba7541..124748a 100644
--- a/core/lib/Drupal/Core/Config/InstallStorage.php
+++ b/core/lib/Drupal/Core/Config/InstallStorage.php
@@ -119,6 +119,7 @@ public function listAll($prefix = '') {
   protected function getAllFolders() {
     if (!isset($this->folders)) {
       $this->folders = array();
+      $this->folders += $this->getComponentNames('core', array('core'));
       // @todo Refactor getComponentNames() to use the extension list directly.
       if ($profile = drupal_get_profile()) {
         $this->folders += $this->getComponentNames('profile', array($profile));
diff --git a/core/lib/Drupal/Core/Config/Schema/SchemaStorage.php b/core/lib/Drupal/Core/Config/Schema/SchemaStorage.php
index 1b84dec..9f5f547 100644
--- a/core/lib/Drupal/Core/Config/Schema/SchemaStorage.php
+++ b/core/lib/Drupal/Core/Config/Schema/SchemaStorage.php
@@ -80,7 +80,8 @@ protected function getAllFolders() {
    */
   protected function getBaseDataTypeSchema() {
     return array(
-      'core.data_types.schema' => 'core/lib/Drupal/Core/Config/Schema'
+      'core.data_types.schema' => 'core/config/schema',
+      'core.extension.schema' => 'core/config/schema',
     );
   }
 
diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index 8172b48..b4d84ca 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -214,8 +214,8 @@ public function discoverServiceProviders() {
     // Ensure we know what modules are enabled and that their namespaces are
     // registered.
     if (!isset($this->moduleList)) {
-      $module_list = $this->getConfigStorage()->read('system.module');
-      $this->moduleList = isset($module_list['enabled']) ? $module_list['enabled'] : array();
+      $module_list = $this->getConfigStorage()->read('core.extension');
+      $this->moduleList = isset($module_list['module']) ? $module_list['module'] : array();
     }
     $module_filenames = $this->getModuleFileNames();
     $this->registerNamespaces($this->getModuleNamespaces($module_filenames));
@@ -414,7 +414,7 @@ protected function initializeContainer() {
 
       // If 'container.modules' is wrong, the container must be rebuilt.
       if (!isset($this->moduleList)) {
-        $this->moduleList = $this->container->get('config.factory')->get('system.module')->get('enabled');
+        $this->moduleList = $this->container->get('config.factory')->get('core.extension')->get('module') ?: array();
       }
       if (array_keys($this->moduleList) !== array_keys($container_modules)) {
         $persist = $this->getServicesToPersist();
diff --git a/core/lib/Drupal/Core/Extension/ModuleHandler.php b/core/lib/Drupal/Core/Extension/ModuleHandler.php
index a20b9b9..802310e 100644
--- a/core/lib/Drupal/Core/Extension/ModuleHandler.php
+++ b/core/lib/Drupal/Core/Extension/ModuleHandler.php
@@ -533,7 +533,7 @@ public static function parseDependency($dependency) {
    * {@inheritdoc}
    */
   public function install(array $module_list, $enable_dependencies = TRUE) {
-    $module_config = \Drupal::config('system.module');
+    $module_config = \Drupal::config('core.extension');
     if ($enable_dependencies) {
       // Get all module data so we can find dependencies and sort.
       $module_data = system_rebuild_module_data();
@@ -544,7 +544,7 @@ public function install(array $module_list, $enable_dependencies = TRUE) {
       }
 
       // Only process currently uninstalled modules.
-      $installed_modules = $module_config->get('enabled') ?: array();
+      $installed_modules = $module_config->get('module') ?: array();
       if (!$module_list = array_diff_key($module_list, $installed_modules)) {
         // Nothing to do. All modules already installed.
         return TRUE;
@@ -584,7 +584,7 @@ public function install(array $module_list, $enable_dependencies = TRUE) {
 
     $modules_installed = array();
     foreach ($module_list as $module) {
-      $enabled = $module_config->get("enabled.$module") !== NULL;
+      $enabled = $module_config->get("module.$module") !== NULL;
       if (!$enabled) {
         // Throw an exception if the module name is too long.
         if (strlen($module) > DRUPAL_EXTENSION_NAME_MAX_LENGTH) {
@@ -595,8 +595,8 @@ public function install(array $module_list, $enable_dependencies = TRUE) {
         }
 
         $module_config
-          ->set("enabled.$module", 0)
-          ->set('enabled', module_config_sort($module_config->get('enabled')))
+          ->set("module.$module", 0)
+          ->set('module', module_config_sort($module_config->get('module')))
           ->save();
 
         // Prepare the new module list, sorted by weight, including filenames.
@@ -610,7 +610,7 @@ public function install(array $module_list, $enable_dependencies = TRUE) {
         // contained in the configured enabled modules, we assume a weight of 0.
         $current_module_filenames = $this->getModuleList();
         $current_modules = array_fill_keys(array_keys($current_module_filenames), 0);
-        $current_modules = module_config_sort(array_merge($current_modules, $module_config->get('enabled')));
+        $current_modules = module_config_sort(array_merge($current_modules, $module_config->get('module')));
         $module_filenames = array();
         foreach ($current_modules as $name => $weight) {
           if (isset($current_module_filenames[$name])) {
@@ -712,8 +712,8 @@ public function uninstall(array $module_list, $uninstall_dependents = TRUE) {
     }
 
     // Only process currently installed modules.
-    $module_config = \Drupal::config('system.module');
-    $installed_modules = $module_config->get('enabled') ?: array();
+    $module_config = \Drupal::config('core.extension');
+    $installed_modules = $module_config->get('module') ?: array();
     if (!$module_list = array_intersect_key($module_list, $installed_modules)) {
       // Nothing to do. All modules already uninstalled.
       return TRUE;
@@ -767,7 +767,7 @@ public function uninstall(array $module_list, $uninstall_dependents = TRUE) {
       drupal_uninstall_schema($module);
 
       // Remove the module's entry from the config.
-      $module_config->clear("enabled.$module")->save();
+      $module_config->clear("module.$module")->save();
 
       // Update the module handler to remove the module.
       // The current ModuleHandler instance is obsolete with the kernel rebuild
diff --git a/core/lib/Drupal/Core/Extension/ThemeHandler.php b/core/lib/Drupal/Core/Extension/ThemeHandler.php
index 35ab1d4..3c5956c 100644
--- a/core/lib/Drupal/Core/Extension/ThemeHandler.php
+++ b/core/lib/Drupal/Core/Extension/ThemeHandler.php
@@ -127,8 +127,7 @@ public function __construct(ConfigFactoryInterface $config_factory, ModuleHandle
    */
   public function enable(array $theme_list) {
     $this->clearCssCache();
-    $theme_config = $this->configFactory->get('system.theme');
-    $disabled_themes = $this->configFactory->get('system.theme.disabled');
+    $theme_config = $this->configFactory->get('core.extension');
     foreach ($theme_list as $key) {
       // Throw an exception if the theme name is too long.
       if (strlen($key) > DRUPAL_EXTENSION_NAME_MAX_LENGTH) {
@@ -139,8 +138,10 @@ public function enable(array $theme_list) {
       }
 
       // The value is not used; the weight is ignored for themes currently.
-      $theme_config->set("enabled.$key", 0)->save();
-      $disabled_themes->clear($key)->save();
+      $theme_config
+        ->set("theme.$key", 0)
+        ->clear("disabled.theme.$key")
+        ->save();
 
       // Refresh the theme list as installation of default configuration needs
       // an updated list to work.
@@ -169,15 +170,14 @@ public function disable(array $theme_list) {
 
     $this->clearCssCache();
 
-    $theme_config = $this->configFactory->get('system.theme');
-    $disabled_themes = $this->configFactory->get('system.theme.disabled');
+    $theme_config = $this->configFactory->get('core.extension');
     foreach ($theme_list as $key) {
       // The value is not used; the weight is ignored for themes currently.
-      $theme_config->clear("enabled.$key");
-      $disabled_themes->set($key, 0);
+      $theme_config
+        ->clear("theme.$key")
+        ->set("disabled.theme.$key", 0);
     }
     $theme_config->save();
-    $disabled_themes->save();
 
     $this->reset();
     $this->resetSystem();
diff --git a/core/lib/Drupal/Core/Extension/UpdateModuleHandler.php b/core/lib/Drupal/Core/Extension/UpdateModuleHandler.php
index 4327aac..d19557c 100644
--- a/core/lib/Drupal/Core/Extension/UpdateModuleHandler.php
+++ b/core/lib/Drupal/Core/Extension/UpdateModuleHandler.php
@@ -80,10 +80,10 @@ public function install(array $module_list, $enable_dependencies = TRUE) {
       }
 
       // Enable the module with a weight of 0.
-      $module_config = \Drupal::config('system.module');
+      $module_config = \Drupal::config('core.extension');
       $module_config
-        ->set("enabled.$module", 0)
-        ->set('enabled', module_config_sort($module_config->get('enabled')))
+        ->set("module.$module", 0)
+        ->set('module', module_config_sort($module_config->get('module')))
         ->save();
 
       $current_schema = $schema_store->get($module);
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigInstallTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigInstallTest.php
index 7188744..f2a10f3 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigInstallTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigInstallTest.php
@@ -75,7 +75,7 @@ function testModuleInstallation() {
     $this->assertIdentical($config->get('integer'), 1);
 
     // Test that uninstalling configuration removes configuration schema.
-    \Drupal::config('system.module')->set('enabled', array())->save();
+    \Drupal::config('core.extension')->set('module', array())->save();
     \Drupal::service('config.manager')->uninstall('module', 'config_test');
     $this->assertFalse(\Drupal::service('config.typed')->hasConfigSchema('config_test.schema_in_install'), 'Configuration schema for config_test.schema_in_install does not exist.');
 
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
index 7737cc8..4ac749e 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
@@ -148,7 +148,7 @@ protected function setUp() {
     // \Drupal\Core\Config\ConfigInstaller::installDefaultConfig() to work.
     // Write directly to active storage to avoid early instantiation of
     // the event dispatcher which can prevent modules from registering events.
-    \Drupal::service('config.storage')->write('system.module', array('enabled' => array()));
+    \Drupal::service('config.storage')->write('core.extension', array('module' => array()));
 
     // Collect and set a fixed module list.
     $class = get_class($this);
@@ -346,14 +346,14 @@ protected function enableModules(array $modules) {
     // Write directly to active storage to avoid early instantiation of
     // the event dispatcher which can prevent modules from registering events.
     $active_storage =  \Drupal::service('config.storage');
-    $system_config = $active_storage->read('system.module');
+    $system_config = $active_storage->read('core.extension');
 
     foreach ($modules as $module) {
       $module_handler->addModule($module, drupal_get_path('module', $module));
       // Maintain the list of enabled modules in configuration.
-      $system_config['enabled'][$module] = 0;
+      $system_config['module'][$module] = 0;
     }
-    $active_storage->write('system.module', $system_config);
+    $active_storage->write('core.extension', $system_config);
 
     // Update the kernel to make their services available.
     $module_filenames = $module_handler->getModuleList();
@@ -382,10 +382,10 @@ protected function disableModules(array $modules) {
     // Unset the list of modules in the extension handler.
     $module_handler = $this->container->get('module_handler');
     $module_filenames = $module_handler->getModuleList();
-    $system_config = $this->container->get('config.factory')->get('system.module');
+    $system_config = $this->container->get('config.factory')->get('core.extension');
     foreach ($modules as $module) {
       unset($module_filenames[$module]);
-      $system_config->clear('enabled.' . $module);
+      $system_config->clear('module.' . $module);
     }
     $system_config->save();
     $module_handler->setModuleList($module_filenames);
diff --git a/core/modules/system/config/schema/system.schema.yml b/core/modules/system/config/schema/system.schema.yml
index 3a14c5c..5f8b4d4 100644
--- a/core/modules/system/config/schema/system.schema.yml
+++ b/core/modules/system/config/schema/system.schema.yml
@@ -274,12 +274,6 @@ system.theme:
     admin:
       type: string
       label: 'Administration theme'
-    enabled:
-      type: sequence
-      label: 'Enabled themes'
-      sequence:
-        - type: integer
-          label: 'Weight'
     default:
       type: string
       label: 'Default theme'
@@ -390,17 +384,6 @@ system.mail:
           type: string
           label: 'Default'
 
-system.module:
-  type: mapping
-  label: 'Module settings'
-  mapping:
-    enabled:
-      type: sequence
-      label: 'Enabled modules'
-      sequence:
-        - type: integer
-          label: 'Weight'
-
 system.theme.global:
   type: mapping
   label: 'Theme global settings'
@@ -465,10 +448,3 @@ system.theme.global:
         use_default:
           type: boolean
           label: 'Use default'
-
-system.theme.disabled:
-  type: sequence
-  label: 'Disabled themes'
-  sequence:
-    - type: integer
-      label: 'Weight'
diff --git a/core/modules/system/config/system.theme.yml b/core/modules/system/config/system.theme.yml
index e88d701..988dc48 100644
--- a/core/modules/system/config/system.theme.yml
+++ b/core/modules/system/config/system.theme.yml
@@ -1,4 +1,2 @@
 admin: ''
-enabled:
-  stark: 0
 default: stark
diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/InstallTest.php b/core/modules/system/lib/Drupal/system/Tests/Module/InstallTest.php
index eaa2fc9..bcaced0 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/InstallTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/InstallTest.php
@@ -48,7 +48,7 @@ public function testGetSchemaAtInstallTime() {
    */
   public function testEnableUserTwice() {
     \Drupal::moduleHandler()->install(array('user'), FALSE);
-    $this->assertIdentical(\Drupal::config('system.module')->get('enabled.user'), 0);
+    $this->assertIdentical(\Drupal::config('core.extension')->get('module.user'), 0);
   }
 
   /**
diff --git a/core/modules/system/lib/Drupal/system/Tests/Update/UpdateScriptTest.php b/core/modules/system/lib/Drupal/system/Tests/Update/UpdateScriptTest.php
index 463b486..cd92191 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Update/UpdateScriptTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Update/UpdateScriptTest.php
@@ -152,10 +152,10 @@ function testThemeSystem() {
     // Since visiting update.php triggers a rebuild of the theme system from an
     // unusual maintenance mode environment, we check that this rebuild did not
     // put any incorrect information about the themes into the database.
-    $original_theme_data = \Drupal::config('system.theme')->get('enabled');
+    $original_theme_data = \Drupal::config('core.extension')->get('theme');
     $this->drupalLogin($this->update_user);
     $this->drupalGet($this->update_url, array('external' => TRUE));
-    $final_theme_data = \Drupal::config('system.theme')->get('enabled');
+    $final_theme_data = \Drupal::config('core.extension')->get('theme');
     $this->assertEqual($original_theme_data, $final_theme_data, 'Visiting update.php does not alter the information about themes stored in the database.');
   }
 
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 7b35fca..4627392 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1287,7 +1287,7 @@ function system_rebuild_module_data() {
     $files = array();
     ksort($modules);
     // Add status, weight, and schema version.
-    $installed_modules = (array) \Drupal::config('system.module')->get('enabled');
+    $installed_modules = (array) \Drupal::config('core.extension')->get('module');
     foreach ($modules as $name => $module) {
       $module->weight = isset($installed_modules[$name]) ? $installed_modules[$name] : 0;
       $module->status = (int) isset($installed_modules[$name]);
@@ -1335,7 +1335,7 @@ function system_rebuild_theme_data() {
   //   based on the current config. Remove this code when themes have a proper
   //   installation status.
   // @see http://drupal.org/node/1067408
-  $enabled_themes = (array) \Drupal::config('system.theme')->get('enabled');
+  $enabled_themes = (array) \Drupal::config('core.extension')->get('theme');
   $files = array();
   foreach ($themes as $name => $theme) {
     $theme->status = (int) isset($enabled_themes[$name]);
diff --git a/core/modules/update/lib/Drupal/update/Tests/UpdateContribTest.php b/core/modules/update/lib/Drupal/update/Tests/UpdateContribTest.php
index a184092..bcb8d0a 100644
--- a/core/modules/update/lib/Drupal/update/Tests/UpdateContribTest.php
+++ b/core/modules/update/lib/Drupal/update/Tests/UpdateContribTest.php
@@ -206,10 +206,10 @@ function testUpdateBaseThemeSecurityUpdate() {
   function testUpdateShowDisabledThemes() {
     $update_settings = \Drupal::config('update.settings');
     // Make sure all the update_test_* themes are disabled.
-    $theme_config = \Drupal::config('system.theme');
-    foreach ($theme_config->get('enabled') as $theme => $weight) {
+    $theme_config = \Drupal::config('core.extension');
+    foreach ($theme_config->get('theme') as $theme => $weight) {
       if (preg_match('/^update_test_/', $theme)) {
-        $theme_config->clear("enabled.$theme");
+        $theme_config->clear("theme.$theme");
       }
     }
     $theme_config->save();
diff --git a/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php b/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php
index 94df741..be72069 100644
--- a/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php
+++ b/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php
@@ -94,7 +94,15 @@ public static function getInfo() {
    * {@inheritdoc}
    */
   protected function setUp() {
-    $this->configFactory = $this->getConfigFactoryStub(array('system.theme' => array(), 'system.theme.disabled' => array()));
+    $this->configFactory = $this->getConfigFactoryStub(array(
+      'core.extension' => array(
+        'module' => array(),
+        'theme' => array(),
+        'disabled' => array(
+          'theme' => array(),
+        ),
+      ),
+    ));
     $this->moduleHandler = $this->getMock('Drupal\Core\Extension\ModuleHandlerInterface');
     $this->cacheBackend = $this->getMock('Drupal\Core\Cache\CacheBackendInterface');
     $this->infoParser = $this->getMock('Drupal\Core\Extension\InfoParserInterface');
@@ -128,21 +136,21 @@ public function testThemeEnableWithTooLongName() {
   public function testEnableSingleTheme() {
     $theme_list = array('theme_test');
 
-    $this->configFactory->get('system.theme')
+    $this->configFactory->get('core.extension')
       ->expects($this->once())
       ->method('set')
-      ->with('enabled.theme_test', 0)
+      ->with('theme.theme_test', 0)
       ->will($this->returnSelf());
-    $this->configFactory->get('system.theme')
+    $this->configFactory->get('core.extension')
       ->expects($this->once())
       ->method('save');
 
-    $this->configFactory->get('system.theme.disabled')
+    $this->configFactory->get('core.extension')
       ->expects($this->once())
       ->method('clear')
-      ->with('theme_test')
+      ->with('disabled.theme.theme_test')
       ->will($this->returnSelf());
-    $this->configFactory->get('system.theme.disabled')
+    $this->configFactory->get('core.extension')
       ->expects($this->once())
       ->method('save');
 
@@ -172,12 +180,12 @@ public function testEnableSingleTheme() {
    * @see \Drupal\Core\Extension\ThemeHandler::listInfo()
    */
   public function testEnableAndListInfo() {
-    $this->configFactory->get('system.theme')
+    $this->configFactory->get('core.extension')
       ->expects($this->exactly(2))
       ->method('set')
       ->will($this->returnSelf());
 
-    $this->configFactory->get('system.theme.disabled')
+    $this->configFactory->get('core.extension')
       ->expects($this->exactly(2))
       ->method('clear')
       ->will($this->returnSelf());