diff --git a/core/includes/config.inc b/core/includes/config.inc
index b4a0666..fde81c7 100644
--- a/core/includes/config.inc
+++ b/core/includes/config.inc
@@ -4,6 +4,7 @@
 use Drupal\Core\Config\FileStorage;
 use Drupal\Core\Config\NullStorage;
 use Drupal\Core\Config\StorageInterface;
+use Symfony\Component\Yaml\Dumper;
 
 /**
  * @file
@@ -324,3 +325,33 @@ function config_get_entity_type_by_name($name) {
 function config_typed() {
   return drupal_container()->get('config.typed');
 }
+
+/**
+ * Return a formatted diff of a named config between two storages.
+ *
+ * @param Drupal\Core\Config\StorageInterface $source_storage
+ *   The storage to diff configuration from.
+ * @param Drupal\Core\Config\StorageInterface $target_storage
+ *   The storage to diff configuration to.
+ * @param string $name
+ *   The name of the configuration object to diff.
+ *
+ * @return core/lib/Drupal/Component/Diff
+ *   A formatted string showing the difference between the two storages.
+ *
+ * @todo Make renderer injectable
+ */
+function config_diff(StorageInterface $source_storage, StorageInterface $target_storage, $name) {
+  require_once DRUPAL_ROOT . '/core/lib/Drupal/Component/Diff/DiffEngine.php';
+
+  // The output should show configuration object differences formatted as YAML.
+  // But the configuration is not necessarily stored in files. Therefore, they
+  // need to be read and parsed, and lastly, dumped into YAML strings.
+  $dumper = new Dumper();
+  $dumper->setIndentation(2);
+
+  $source_data = explode("\n", $dumper->dump($source_storage->read($name), PHP_INT_MAX));
+  $target_data = explode("\n", $dumper->dump($target_storage->read($name), PHP_INT_MAX));
+
+  return new Diff($source_data, $target_data);
+}
diff --git a/core/lib/Drupal/Component/Diff/DiffEngine.php b/core/lib/Drupal/Component/Diff/DiffEngine.php
index 1236610..f426b96 100644
--- a/core/lib/Drupal/Component/Diff/DiffEngine.php
+++ b/core/lib/Drupal/Component/Diff/DiffEngine.php
@@ -1111,11 +1111,11 @@ function _end_diff() {
   function _block_header($xbeg, $xlen, $ybeg, $ylen) {
     return array(
       array(
-        'data' => theme('diff_header_line', array('lineno' => $xbeg + $this->line_stats['offset']['x'])),
+        'data' => $xbeg + $this->line_stats['offset']['x'],
         'colspan' => 2,
       ),
       array(
-        'data' => theme('diff_header_line', array('lineno' => $ybeg + $this->line_stats['offset']['y'])),
+        'data' => $ybeg + $this->line_stats['offset']['y'],
         'colspan' => 2,
       )
     );
@@ -1143,7 +1143,7 @@ function addedLine($line) {
         'class' => 'diff-marker',
       ),
       array(
-        'data' => theme('diff_content_line', array('line' => $line)),
+        'data' => $line,
         'class' => 'diff-context diff-addedline',
       )
     );
@@ -1159,7 +1159,7 @@ function deletedLine($line) {
         'class' => 'diff-marker',
       ),
       array(
-        'data' => theme('diff_content_line', array('line' => $line)),
+        'data' => $line,
         'class' => 'diff-context diff-deletedline',
       )
     );
@@ -1172,7 +1172,7 @@ function contextLine($line) {
     return array(
       ' ',
       array(
-        'data' => theme('diff_content_line', array('line' => $line)),
+        'data' => $line,
         'class' => 'diff-context',
       )
     );
@@ -1181,7 +1181,7 @@ function contextLine($line) {
   function emptyLine() {
     return array(
       ' ',
-      theme('diff_empty_line', array('line' => ' ')),
+      ' ',
     );
   }
 
diff --git a/core/modules/config/config.admin.inc b/core/modules/config/config.admin.inc
index 3813885..81b568d 100644
--- a/core/modules/config/config.admin.inc
+++ b/core/modules/config/config.admin.inc
@@ -41,6 +41,7 @@ function config_admin_sync_form(array &$form, array &$form_state, StorageInterfa
     if (empty($config_files)) {
       continue;
     }
+
     // @todo A table caption would be more appropriate, but does not have the
     //   visual importance of a heading.
     $form[$config_change_type]['heading'] = array(
@@ -62,10 +63,21 @@ function config_admin_sync_form(array &$form, array &$form_state, StorageInterfa
     }
     $form[$config_change_type]['list'] = array(
       '#theme' => 'table',
-      '#header' => array('Name'),
+      '#header' => array('Name', 'Operations'),
     );
+
     foreach ($config_files as $config_file) {
-      $form[$config_change_type]['list']['#rows'][] = array($config_file);
+      $form[$config_change_type]['list']['#rows'][] = array(
+        'name' => $config_file,
+        'operations' => array(
+          'data' => array(
+            '#type' => 'link',
+            '#title' => t('Diff'),
+            '#href' => 'admin/config/development/sync/diff/' . $config_file,
+            '#ajax' => array('dialog' => array('modal' =>TRUE, 'width' => '700px')),
+          ),
+        ),
+      );
     }
   }
 }
@@ -116,3 +128,54 @@ function config_admin_import_form_submit($form, &$form_state) {
     drupal_set_message(t('The import failed due to an error. Any errors have been logged.'), 'error');
   }
 }
+
+/**
+ * Page callback: Shows diff of specificed configuration file.
+ *
+ * @param string $config_file
+ *   The name of the configuration file.
+ *
+ * @return string
+ *   Table showing a two-way diff between the active and staged configuration.
+ */
+function config_admin_diff_page($config_file) {
+  // Retrieve a list of differences between last known state and active store.
+  $source_storage = drupal_container()->get('config.storage.staging');
+  $target_storage = drupal_container()->get('config.storage');
+
+  // Add the CSS for the inline diff.
+  $output['#attached']['css'][] = drupal_get_path('module', 'system') . '/system.diff.css';
+
+  $output['title'] = array(
+    '#theme' => 'html_tag__h3',
+    '#tag' => 'h3',
+    '#value' => t('View changes of @config_file', array('@config_file' => $config_file)),
+  );
+
+  $diff = config_diff($target_storage, $source_storage, $config_file);
+  $formatter = new DrupalDiffFormatter();
+  $formatter->show_header = FALSE;
+
+  $variables = array(
+    'header' => array(
+      array('data' => t('Old'), 'colspan' => '2'),
+      array('data' => t('New'), 'colspan' => '2'),
+    ),
+    'rows' => $formatter->format($diff),
+  );
+
+  $output['diff'] = array(
+    '#markup' => theme('table', $variables),
+  );
+
+  $output['back'] = array(
+    '#type' => 'link',
+    '#title' => "Back to 'Synchronize configuration' page.",
+    '#href' => 'admin/config/development/sync',
+    '#attributes' => array(
+      'class' => array('dialog-cancel'),
+    ),
+  );
+
+  return $output;
+}
diff --git a/core/modules/config/config.module b/core/modules/config/config.module
index a41fc09..7482171 100644
--- a/core/modules/config/config.module
+++ b/core/modules/config/config.module
@@ -48,6 +48,14 @@ function config_menu() {
     'access arguments' => array('synchronize configuration'),
     'file' => 'config.admin.inc',
   );
+  $items['admin/config/development/sync/diff/%'] = array(
+    'title' => 'Configuration file diff',
+    'description' => 'Diff between active and staged configuraiton.',
+    'page callback' => 'config_admin_diff_page',
+    'page arguments' => array(5),
+    'access arguments' => array('synchronize configuration'),
+    'file' => 'config.admin.inc',
+  );
   $items['admin/config/development/sync/import'] = array(
     'title' => 'Import',
     'type' => MENU_DEFAULT_LOCAL_TASK,
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigDiffTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigDiffTest.php
new file mode 100644
index 0000000..09f126b
--- /dev/null
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigDiffTest.php
@@ -0,0 +1,89 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config\Tests\ConfigDiffTest.
+ */
+
+namespace Drupal\config\Tests;
+
+use Drupal\simpletest\DrupalUnitTestBase;
+
+/**
+ * Tests config snapshot creation and updating.
+ */
+class ConfigDiffTest extends DrupalUnitTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('config_test', 'system');
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Diff functionality',
+      'description' => 'Calculating the difference between two sets of configuration.',
+      'group' => 'Configuration',
+    );
+  }
+
+  /**
+   * Tests calculating the difference between two sets of configuration.
+   */
+  function testDiff() {
+    $active = $this->container->get('config.storage');
+    $staging = $this->container->get('config.storage.staging');
+    $config_name = 'config_test.system';
+    $change_key = 'foo';
+    $remove_key = '404';
+    $add_key = 'biff';
+    $add_data = 'bangpow';
+    $change_data = 'foobar';
+    $original_data = array(
+      'foo' => 'bar',
+      '404' => 'herp',
+    );
+
+    // Install the default config.
+    config_install_default_config('module', 'config_test');
+
+    // Change a configuration value in staging.
+    $staging_data = $original_data;
+    $staging_data[$change_key] = $change_data;
+    $staging_data[$add_key] = $add_data;
+    $staging->write($config_name, $staging_data);
+
+    // Verify that the diff reflects a change.
+    $diff = config_diff($active, $staging, $config_name);
+    $this->assertEqual($diff->edits[0]->type, 'change', 'The first item in the diff is a change.');
+    $this->assertEqual($diff->edits[0]->orig[0], $change_key . ': ' . $original_data[$change_key], format_string("The active value for key '%change_key' is '%original_data'.", array('%change_key' => $change_key, '%original_data' => $original_data[$change_key])));
+    $this->assertEqual($diff->edits[0]->closing[0], $change_key . ': ' . $change_data, format_string("The staging value for key '%change_key' is '%change_data'.", array('%change_key' => $change_key, '%change_data' => $change_data)));
+
+    // Reset data back to original, and remove a key
+    $staging_data = $original_data;
+    unset($staging_data[$remove_key]);
+    $staging->write($config_name, $staging_data);
+
+    // Verify that the diff reflects a removed key.
+    $diff = config_diff($active, $staging, $config_name);
+    $this->assertEqual($diff->edits[0]->type, 'copy', 'The first item in the diff is a copy.');
+    $this->assertEqual($diff->edits[1]->type, 'delete', 'The second item in the diff is a delete.');
+    $this->assertEqual($diff->edits[1]->orig[0], $remove_key . ': ' . $original_data[$remove_key], format_string("The active value for key '%remove_key' is '%original_data'.", array('%remove_key' => $remove_key, '%original_data' => $original_data[$remove_key])));
+    $this->assertFalse($diff->edits[1]->closing, format_string("The key '%remove_key' does not exist in staging.", array('%remove_key' => $remove_key)));
+
+    // Reset data back to original and add a key
+    $staging_data = $original_data;
+    $staging_data[$add_key] = $add_data;
+    $staging->write($config_name, $staging_data);
+
+    // Verify that the diff reflects an added key.
+    $diff = config_diff($active, $staging, $config_name);
+    $this->assertEqual($diff->edits[0]->type, 'copy', 'The first item in the diff is a copy.');
+    $this->assertEqual($diff->edits[1]->type, 'add', 'The second item in the diff is an add.');
+    $this->assertFalse($diff->edits[1]->orig, format_string("The key '%add_key' does not exist in active.", array('%add_key' => $add_key)));
+    $this->assertEqual($diff->edits[1]->closing[0], $add_key . ': ' . $add_data, format_string("The staging value for key '%add_key' is '%add_data'.", array('%add_key' => $add_key, '%add_data' => $add_data)));
+  }
+
+}
\ No newline at end of file
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
index 7900b7b..3788d67 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
@@ -126,6 +126,49 @@ function testImportLock() {
     $this->assertNotEqual($new_site_name, config('system.site')->get('name'));
   }
 
+  /**
+   * Tests the screen that shows differences between active and staging.
+   */
+  function testImportDiff() {
+    $active = $this->container->get('config.storage');
+    $staging = $this->container->get('config.storage.staging');
+    $config_name = 'config_test.system';
+    $change_key = 'foo';
+    $remove_key = '404';
+    $add_key = 'biff';
+    $add_data = 'bangpow';
+    $change_data = 'foobar';
+    $original_data = array(
+      'foo' => 'bar',
+      '404' => 'herp',
+    );
+
+    // Change a configuration value in staging.
+    $staging_data = $original_data;
+    $staging_data[$change_key] = $change_data;
+    $staging_data[$add_key] = $add_data;
+    $staging->write($config_name, $staging_data);
+
+    // Load the diff UI and verify that the diff reflects the change.
+    $this->drupalGet('admin/config/development/sync/diff/' . $config_name);
+
+    // Reset data back to original, and remove a key
+    $staging_data = $original_data;
+    unset($staging_data[$remove_key]);
+    $staging->write($config_name, $staging_data);
+
+    // Load the diff UI and verify that the diff reflects a removed key.
+    $this->drupalGet('admin/config/development/sync/diff/' . $config_name);
+
+    // Reset data back to original and add a key
+    $staging_data = $original_data;
+    $staging_data[$add_key] = $add_data;
+    $staging->write($config_name, $staging_data);
+
+    // Load the diff UI and verify that the diff reflects an added key.
+    $this->drupalGet('admin/config/development/sync/diff/' . $config_name);
+  }
+
   function prepareSiteNameUpdate($new_site_name) {
     $staging = $this->container->get('config.storage.staging');
     // Create updated configuration object.
diff --git a/core/modules/system/system.diff.css b/core/modules/system/system.diff.css
new file mode 100644
index 0000000..252a049
--- /dev/null
+++ b/core/modules/system/system.diff.css
@@ -0,0 +1,83 @@
+/**
+ * Inline diff metadata
+ */
+.diff-inline-metadata {
+  padding:4px;
+  border:1px solid #ddd;
+  background:#fff;
+  margin:0px 0px 10px;
+}
+
+.diff-inline-legend { font-size:11px; }
+
+.diff-inline-legend span,
+.diff-inline-legend label { margin-right:5px; }
+
+/**
+ * Inline diff markup
+ */
+span.diff-deleted { color:#ccc; }
+span.diff-deleted img { border: solid 2px #ccc; }
+span.diff-changed { background:#ffb; }
+span.diff-changed img { border:solid 2px #ffb; }
+span.diff-added { background:#cfc; }
+span.diff-added img { border: solid 2px #cfc; }
+
+/**
+ * Traditional split diff theming
+ */
+table.diff {
+  border-spacing: 4px;
+  margin-bottom: 20px;
+  table-layout: fixed;
+  width: 100%;
+}
+table.diff tr.even, table.diff tr.odd {
+  background-color: inherit;
+  border: none;
+}
+td.diff-prevlink {
+  text-align: left;
+}
+td.diff-nextlink {
+  text-align: right;
+}
+td.diff-section-title, div.diff-section-title {
+  background-color: #f0f0ff;
+  font-size: 0.83em;
+  font-weight: bold;
+  padding: 0.1em 1em;
+}
+td.diff-deletedline {
+  background-color: #ffa;
+  width: 50%;
+}
+td.diff-addedline {
+  background-color: #afa;
+  width: 50%;
+}
+td.diff-context {
+  background-color: #fafafa;
+}
+span.diffchange {
+  color: #f00;
+  font-weight: bold;
+}
+
+table.diff col.diff-marker {
+  width: 1.4em;
+}
+table.diff col.diff-content {
+  width: 50%;
+}
+table.diff th {
+  padding-right: inherit;
+}
+table.diff td div {
+  overflow: auto;
+  padding: 0.1ex 0.5em;
+  word-wrap: break-word;
+}
+table.diff td {
+  padding: 0.1ex 0.4em;
+}