diff --git a/restful.module b/restful.module
index 1d9b0159..923865d0 100644
--- a/restful.module
+++ b/restful.module
@@ -273,7 +273,7 @@ function restful_menu_process_callback($resource_name, $version = NULL) {
 
   try {
     $resource->setPath(implode('/', $path));
-    return $resource->process();
+    $result = $resource->process();
   }
   catch (RestfulException $e) {
     $result = _restful_build_http_api_error($e);
@@ -286,6 +286,8 @@ function restful_menu_process_callback($resource_name, $version = NULL) {
     );
   }
 
+  // If the user was switched during the execution thread, then switch it back.
+  $resource->switchUserBack();
   return $result;
 }
 
diff --git a/src/Authentication/AuthenticationManager.php b/src/Authentication/AuthenticationManager.php
index 2f0e059b..447c3177 100644
--- a/src/Authentication/AuthenticationManager.php
+++ b/src/Authentication/AuthenticationManager.php
@@ -12,6 +12,11 @@
 use Drupal\restful\Plugin\AuthenticationPluginManager;
 use Drupal\restful\RestfulManager;
 
+/**
+ * Class AuthenticationManager.
+ *
+ * @package Drupal\restful\Authentication
+ */
 class AuthenticationManager implements AuthenticationManagerInterface {
 
   /**
@@ -38,14 +43,22 @@ class AuthenticationManager implements AuthenticationManagerInterface {
    */
   protected $isOptional = FALSE;
 
+  /**
+   * User session state to switch user for the Drupal thread.
+   *
+   * @var UserSessionStateInterface
+   */
+  protected $userSessionState;
+
   /**
    * Constructs a new AuthenticationManager object.
    *
    * @param AuthenticationPluginManager $manager
    *   The authentication plugin manager.
    */
-  public function __construct(AuthenticationPluginManager $manager = NULL) {
+  public function __construct(AuthenticationPluginManager $manager = NULL, UserSessionStateInterface $user_session_state = NULL) {
     $this->plugins = new AuthenticationPluginCollection($manager ?: AuthenticationPluginManager::create());
+    $this->userSessionState = $user_session_state ?: new UserSessionState();
   }
 
   /**
@@ -143,6 +156,16 @@ public function getAccount(RequestInterface $request, $cache = TRUE) {
    */
   public function setAccount($account) {
     $this->account = $account;
+    if (!empty($account->uid)) {
+      $this->userSessionState->switchUser($account);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function switchUserBack() {
+    return $this->userSessionState->switchUserBack();
   }
 
   /**
diff --git a/src/Authentication/AuthenticationManagerInterface.php b/src/Authentication/AuthenticationManagerInterface.php
index 018ef747..4f511b14 100644
--- a/src/Authentication/AuthenticationManagerInterface.php
+++ b/src/Authentication/AuthenticationManagerInterface.php
@@ -47,15 +47,15 @@ public function addAllAuthenticationProviders();
   /**
    * Get the user account for the request.
    *
-   * @param array $request
+   * @param RequestInterface $request
    *   The request.
-   * @param string $method
-   *   The HTTP method.
-   * @param boolean $cache
+   * @param bool $cache
    *   Boolean indicating if the resolved user should be cached for next calls.
    *
    * @throws UnauthorizedException
-   * @return \stdClass
+   *   When bad credentials are provided.
+   *
+   * @return object
    *   The user object.
    */
   public function getAccount(RequestInterface $request, $cache = TRUE);
@@ -68,10 +68,16 @@ public function getAccount(RequestInterface $request, $cache = TRUE);
    */
   public function setAccount($account);
 
+  /**
+   * Switches the user back from the original user for the session.
+   */
+  public function switchUserBack();
+
   /**
    * Gets the plugin collection for this plugin manager.
    *
    * @return AuthenticationPluginManager
+   *   The plugin manager.
    */
   public function getPlugins();
 
diff --git a/src/Authentication/UserSessionState.php b/src/Authentication/UserSessionState.php
new file mode 100644
index 00000000..933735c9
--- /dev/null
+++ b/src/Authentication/UserSessionState.php
@@ -0,0 +1,98 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\restful\Authentication\UserSessionState.
+ */
+
+namespace Drupal\restful\Authentication;
+
+/**
+ * Class UserSessionState.
+ *
+ * @package Drupal\restful\Authentication
+ */
+class UserSessionState implements UserSessionStateInterface {
+
+  /**
+   * Boolean holding if this is the first switch.
+   *
+   * @var bool
+   */
+  protected static $isSwitched = FALSE;
+
+  /**
+   * Boolean holding if the session needs to be saved.
+   *
+   * @var bool
+   */
+  protected $needsSaving = FALSE;
+
+  /**
+   * Object holding the original user.
+   *
+   * This is saved for switch back purposes.
+   *
+   * @var object
+   */
+  protected $originalUser;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function isSwitched() {
+    return static::$isSwitched;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function switchUser($account) {
+    global $user;
+
+    if (!static::isSwitched() && !$this->originalUser && !$this->needsSaving) {
+      // This is the first time a user switched, and there isn't an original
+      // user session.
+      $this->needsSaving = drupal_save_session();
+      $this->originalUser = $user;
+
+      // Don't allow a session to be saved. Provider that require a session to
+      // be saved, like the cookie provider, need to explicitly set
+      // drupal_save_session(TRUE).
+      // @see LoginCookie__1_0::loginUser().
+      drupal_save_session(FALSE);
+    }
+
+    // Set the global user.
+    $user = $account;
+  }
+
+  /**
+   * Switch the user to the authenticated user, and back.
+   *
+   * This should be called only for an API call. It should not be used for calls
+   * via the menu system, as it might be a login request, so we avoid switching
+   * back to the anonymous user.
+   */
+  public function switchUserBack() {
+    global $user;
+    if (!$this->originalUser) {
+      return;
+    }
+
+    $user = $this->originalUser;
+    drupal_save_session($this->needsSaving);
+    $this->reset();
+  }
+
+  /**
+   * Reset the initial values.
+   */
+  protected function reset() {
+    // Reset initial values.
+    static::$isSwitched = FALSE;
+    $this->originalUser = NULL;
+    $this->needsSaving = FALSE;
+  }
+
+}
diff --git a/src/Authentication/UserSessionStateInterface.php b/src/Authentication/UserSessionStateInterface.php
new file mode 100644
index 00000000..e76c160f
--- /dev/null
+++ b/src/Authentication/UserSessionStateInterface.php
@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\restful\Authentication\UserSessionStateInterface.
+ */
+
+namespace Drupal\restful\Authentication;
+
+/**
+ * Class UserSessionStateInterface.
+ *
+ * @package Drupal\restful\Authentication
+ */
+interface UserSessionStateInterface {
+
+  /**
+   * Check if the user has already been switched.
+   *
+   * We need this information to perform additional actions the first time a
+   * user is switched.
+   *
+   * @return bool
+   *   TRUE if the user has been switched previously. FALSE otherwise.
+   */
+  public static function isSwitched();
+
+  /**
+   * Make the passed in user to be the account for the Drupal thread.
+   *
+   * @param object $account
+   *   The account to switch to.
+   */
+  public function switchUser($account);
+
+  /**
+   * Switch the user to the authenticated user, and back.
+   *
+   * This should be called only for an API call. It should not be used for calls
+   * via the menu system, as it might be a login request, so we avoid switching
+   * back to the anonymous user.
+   */
+  public function switchUserBack();
+
+}
diff --git a/src/Plugin/resource/Decorators/CacheDecoratedResource.php b/src/Plugin/resource/Decorators/CacheDecoratedResource.php
index 6931615c..b504f9e4 100644
--- a/src/Plugin/resource/Decorators/CacheDecoratedResource.php
+++ b/src/Plugin/resource/Decorators/CacheDecoratedResource.php
@@ -286,13 +286,6 @@ public function isEnabled() {
     return $this->subject->isEnabled();
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function discover($path = NULL) {
-    return $this->subject->discover($path);
-  }
-
   /**
    * {@inheritdoc}
    */
diff --git a/src/Plugin/resource/Decorators/RateLimitDecoratedResource.php b/src/Plugin/resource/Decorators/RateLimitDecoratedResource.php
index 1cdb7144..1842532e 100644
--- a/src/Plugin/resource/Decorators/RateLimitDecoratedResource.php
+++ b/src/Plugin/resource/Decorators/RateLimitDecoratedResource.php
@@ -7,12 +7,14 @@
 
 namespace Drupal\restful\Plugin\resource\Decorators;
 
-use Drupal\restful\Http\RequestInterface;
-use Drupal\restful\Plugin\resource\DataProvider\DataProviderInterface;
-use Drupal\restful\Plugin\resource\Field\ResourceFieldCollection;
 use Drupal\restful\Plugin\resource\ResourceInterface;
 use Drupal\restful\RateLimit\RateLimitManager;
 
+/**
+ * Class RateLimitDecoratedResource.
+ *
+ * @package Drupal\restful\Plugin\resource\Decorators
+ */
 class RateLimitDecoratedResource extends ResourceDecoratorBase implements ResourceDecoratorInterface {
 
   /**
@@ -83,11 +85,4 @@ public function setAccount($account) {
     $this->rateLimitManager->setAccount($account);
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function discover($path = NULL) {
-    return $this->subject->discover($path);
-  }
-
 }
diff --git a/src/Plugin/resource/Decorators/ResourceDecoratorBase.php b/src/Plugin/resource/Decorators/ResourceDecoratorBase.php
index 451100a2..5992b432 100644
--- a/src/Plugin/resource/Decorators/ResourceDecoratorBase.php
+++ b/src/Plugin/resource/Decorators/ResourceDecoratorBase.php
@@ -16,6 +16,11 @@
 use Drupal\restful\Plugin\resource\Field\ResourceFieldCollectionInterface;
 use Drupal\restful\Plugin\resource\ResourceInterface;
 
+/**
+ * Class ResourceDecoratorBase.
+ *
+ * @package Drupal\restful\Plugin\resource\Decorators
+ */
 abstract class ResourceDecoratorBase extends PluginBase implements ResourceDecoratorInterface {
 
   /**
@@ -51,8 +56,6 @@ public function dataProviderFactory() {
   }
 
   /**
-   * Proxy method to get the account from the rateLimitManager.
-   *
    * {@inheritdoc}
    */
   public function getAccount($cache = TRUE) {
@@ -60,8 +63,6 @@ public function getAccount($cache = TRUE) {
   }
 
   /**
-   * Proxy method to get the account from the rateLimitManager.
-   *
    * {@inheritdoc}
    */
   public function setAccount($account) {
@@ -69,6 +70,20 @@ public function setAccount($account) {
     $this->getDataProvider()->setAccount($account);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function switchUserBack() {
+    $this->subject->switchUserBack();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function discover($path = NULL) {
+    return $this->subject->discover($path);
+  }
+
   /**
    * {@inheritdoc}
    */
diff --git a/src/Plugin/resource/LoginCookie__1_0.php b/src/Plugin/resource/LoginCookie__1_0.php
index 4af2df65..801c9d6d 100644
--- a/src/Plugin/resource/LoginCookie__1_0.php
+++ b/src/Plugin/resource/LoginCookie__1_0.php
@@ -92,6 +92,13 @@ public function loginAndRespondWithCookie() {
    */
   public function loginUser($account) {
     global $user;
+
+    $this->authenticationManager->switchUserBack();
+    // Explicitly allow a session to be saved, as it was disabled in
+    // UserSessionState::switchUser. However this resource is a special one, in
+    // the sense that we want to keep the user authenticated after login.
+    drupal_save_session(TRUE);
+
     // Override the global user.
     $user = user_load($account->uid);
 
@@ -110,4 +117,12 @@ public static function getCSRFTokenValue() {
     return reset($token);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function switchUserBack() {
+    // We don't want to switch back in this case!
+    drupal_save_session(TRUE);
+  }
+
 }
diff --git a/src/Plugin/resource/Resource.php b/src/Plugin/resource/Resource.php
index 5feb3043..40b50a3e 100644
--- a/src/Plugin/resource/Resource.php
+++ b/src/Plugin/resource/Resource.php
@@ -121,6 +121,13 @@ public function getAccount($cache = TRUE) {
     return $this->authenticationManager->getAccount($this->getRequest(), $cache);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function switchUserBack() {
+    return $this->authenticationManager->switchUserBack();
+  }
+
   /**
    * {@inheritdoc}
    */
diff --git a/src/Plugin/resource/ResourceInterface.php b/src/Plugin/resource/ResourceInterface.php
index 38ba0078..5044fc30 100644
--- a/src/Plugin/resource/ResourceInterface.php
+++ b/src/Plugin/resource/ResourceInterface.php
@@ -20,6 +20,11 @@
 use Drupal\restful\Plugin\resource\Field\ResourceFieldCollection;
 use Drupal\restful\Plugin\resource\Field\ResourceFieldCollectionInterface;
 
+/**
+ * Interface ResourceInterface.
+ *
+ * @package Drupal\restful\Plugin\resource
+ */
 interface ResourceInterface extends PluginInspectionInterface, ConfigurablePluginInterface {
 
   /**
@@ -51,6 +56,11 @@ public function dataProviderFactory();
    */
   public function getAccount($cache = TRUE);
 
+  /**
+   * Switches the user back from the original user for the session.
+   */
+  public function switchUserBack();
+
   /**
    * {@inheritdoc}
    */
diff --git a/tests/RestfulUserLoginCookieTestCase.test b/tests/RestfulUserLoginCookieTestCase.test
index da933fc3..5745acf8 100644
--- a/tests/RestfulUserLoginCookieTestCase.test
+++ b/tests/RestfulUserLoginCookieTestCase.test
@@ -21,6 +21,9 @@ class RestfulUserLoginCookieTestCase extends RestfulCurlBaseTestCase {
    */
   protected $originalServer;
 
+  /**
+   * {@inheritdoc}
+   */
   public static function getInfo() {
     return array(
       'name' => 'Login endpoint',
@@ -29,13 +32,19 @@ class RestfulUserLoginCookieTestCase extends RestfulCurlBaseTestCase {
     );
   }
 
-  function setUp() {
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
     parent::setUp('restful');
 
     $this->originalServer = $_SERVER;
   }
 
-  function tearDown() {
+  /**
+   * {@inheritdoc}
+   */
+  public function tearDown() {
     global $user;
     // Put back the user object.
     $user = $this->originalUser;
@@ -48,7 +57,7 @@ class RestfulUserLoginCookieTestCase extends RestfulCurlBaseTestCase {
   /**
    * Test login using curl via /api/login.
    */
-  function testLogin() {
+  public function testLogin() {
     global $user;
     // We need to hijack the global user object in order to force it to be an
     // anonymous user.