diff --git a/includes/datastream.inc b/includes/datastream.inc
index da55dcd5..585fa2f5 100644
--- a/includes/datastream.inc
+++ b/includes/datastream.inc
@@ -30,6 +30,13 @@ function islandora_download_datastream(AbstractDatastream $datastream) {
  *   The version of the datastream to display
  */
 function islandora_view_datastream(AbstractDatastream $datastream, $download = FALSE, $version = NULL) {
+  // XXX: Certain features of the Devel module rely on the use of "shutdown
+  // handlers", such as query logging... The problem is that they might blindly
+  // add additional output which will break things if what is actually being
+  // output is anything but a webpage... like an image or video or audio or
+  // whatever the datastream is here.
+  $GLOBALS['devel_shutdown'] = FALSE;
+
   if ($version !== NULL) {
     if (isset($datastream[$version])) {
       $datastream = $datastream[$version];
diff --git a/includes/datastream.version.inc b/includes/datastream.version.inc
index 1e7c0830..507a182f 100644
--- a/includes/datastream.version.inc
+++ b/includes/datastream.version.inc
@@ -18,7 +18,7 @@ function islandora_datastream_version_table($datastream) {
   $header[] = array('data' => t('Size'));
   $header[] = array('data' => t('Label'));
   $header[] = array('data' => t('Mime type'));
-  $header[] = array('data' => t('Operations'));
+  $header[] = array('data' => t('Operations'), 'colspan' => '2');
   $rows = array();
 
   foreach ($datastream as $version => $datastream_version) {
@@ -50,6 +50,13 @@ function islandora_datastream_version_table($datastream) {
         'version' => $version,
       )),
     );
+    $row[] = array(
+      'class' => 'datastream-revert',
+      'data' => theme('islandora_datastream_revert_link', array(
+        'datastream' => $datastream,
+        'version' => $version,
+      )),
+    );
     $rows[] = $row;
   }
 
@@ -125,3 +132,79 @@ function islandora_delete_datastream_version_form_submit(array $form, array &$fo
 
   $form_state['redirect'] = "islandora/object/{$object->id}/datastream/{$datastream->id}/version";
 }
+
+/**
+ * The admin revert datastream form.
+ *
+ * @param array $form
+ *   The Drupal form.
+ * @param array $form_state
+ *   The Drupal form state.
+ * @param AbstractDatastream $datastream
+ *   The datastream to be deleted.
+ * @param string $version
+ *   The version number of the datastream we are trying to revert to.
+ *
+ * @return array
+ *   The drupal form definition.
+ */
+function islandora_revert_datastream_version_form(array $form, array &$form_state, AbstractDatastream $datastream, $version) {
+  if (!isset($datastream[$version]) || count($datastream) < 2) {
+    return drupal_not_found();
+  }
+
+  $form_state['dsid'] = $datastream->id;
+  $form_state['object_id'] = $datastream->parent->id;
+  $form_state['version'] = $version;
+
+  return confirm_form($form,
+    t('Are you sure you want to revert to version @version of the @dsid datastream?', array('@dsid' => $datastream->id, '@version' => $version)),
+    "islandora/object/{$datastream->parent->id}",
+    "",
+    t('Revert'),
+    t('Cancel')
+  );
+}
+
+/**
+ * Submit handler for the revert datastream form.
+ *
+ * Reverts the given AbstractDatastream if possible.
+ *
+ * @param array $form
+ *   The Drupal form.
+ * @param array $form_state
+ *   The Drupal form state.
+ */
+function islandora_revert_datastream_version_form_submit(array $form, array &$form_state) {
+  $islandora_object = islandora_object_load($form_state['object_id']);
+
+  $datastream_to_revert = $islandora_object[$form_state['dsid']];
+  $version = $form_state['version'];
+
+  // Create file holding specified datastream version, and set datastream to it.
+  $datastream_to_revert_to = $datastream_to_revert[$version];
+  if (in_array($datastream_to_revert->controlGroup, array('R', 'E'))) {
+    $datastream_to_revert->url = $datastream_to_revert_to->url;
+  }
+  else {
+    $filename = file_create_filename('datastream_temp_file', 'temporary://');
+    $datastream_to_revert_to->getContent($filename);
+    $datastream_to_revert->setContentFromFile($filename);
+    file_unmanaged_delete($filename);
+  }
+
+  if ($datastream_to_revert->mimeType != $datastream_to_revert_to->mimeType) {
+    $datastream_to_revert->mimeType = $datastream_to_revert_to->mimeType;
+  }
+  if ($datastream_to_revert->label != $datastream_to_revert_to->label) {
+    $datastream_to_revert->label = $datastream_to_revert_to->label;
+  }
+
+  drupal_set_message(t('%d datastream successfully reverted to version %v for Islandora object %o', array(
+        '%d' => $datastream_to_revert->id,
+        '%v' => $version,
+        '%o' => $islandora_object->label)));
+
+  $form_state['redirect'] = "islandora/object/{$islandora_object->id}/datastream/{$datastream_to_revert->id}/version";
+}
diff --git a/includes/derivatives.inc b/includes/derivatives.inc
index 4a422535..fbf4b9e7 100644
--- a/includes/derivatives.inc
+++ b/includes/derivatives.inc
@@ -98,7 +98,7 @@ function islandora_derivative_logging(array $logging_results) {
         // message and the substitutions needed. We are using
         // call_user_func until such time as the @ignore changes
         // are merged into the standard release for Coder.
-        call_user_func('watchdog', $message['message'], isset($message['message_sub']) ? $message['message_sub'] : array(), isset($message['severity']) ? $message['severity'] : WATCHDOG_NOTICE);
+        call_user_func('watchdog', 'islandora_derivatives', $message['message'], isset($message['message_sub']) ? $message['message_sub'] : array(), isset($message['severity']) ? $message['severity'] : WATCHDOG_NOTICE);
       }
     }
   }
diff --git a/islandora.api.php b/islandora.api.php
index e0cc86b6..2e6ef831 100644
--- a/islandora.api.php
+++ b/islandora.api.php
@@ -477,10 +477,11 @@ function hook_CMODEL_PID_islandora_ingest_steps(array $form_state) {
  * @param object $user
  *   A loaded user object, as the global $user variable might contain.
  *
- * @return bool|NULL
+ * @return bool|NULL|array
  *   Either boolean TRUE or FALSE to explicitly allow or deny the operation on
  *   the given object, or NULL to indicate that we are making no assertion
- *   about the outcome.
+ *   about the outcome. Can also be an array containing multiple
+ *   TRUE/FALSE/NULLs, due to how hooks work.
  */
 function hook_islandora_object_access($op, $object, $user) {
   switch ($op) {
@@ -515,10 +516,11 @@ function hook_CMODEL_PID_islandora_object_access($op, $object, $user) {
  * @param object $user
  *   A loaded user object, as the global $user variable might contain.
  *
- * @return bool|NULL
+ * @return bool|NULL|array
  *   Either boolean TRUE or FALSE to explicitly allow or deny the operation on
  *   the given object, or NULL to indicate that we are making no assertion
- *   about the outcome.
+ *   about the outcome. Can also be an array containing multiple
+ *   TRUE/FALSE/NULLs, due to how hooks work.
  */
 function hook_islandora_datastream_access($op, $object, $user) {
   switch ($op) {
diff --git a/islandora.module b/islandora.module
index eb05211e..9df17892 100644
--- a/islandora.module
+++ b/islandora.module
@@ -35,6 +35,8 @@ define('ISLANDORA_PURGE', 'delete fedora objects and datastreams');
 define('ISLANDORA_MANAGE_PROPERTIES', 'manage object properties');
 define('ISLANDORA_VIEW_DATASTREAM_HISTORY', 'view old datastream versions');
 define('ISLANDORA_MANAGE_DELETED_OBJECTS', 'manage deleted objects');
+define('ISLANDORA_REVERT_DATASTREAM', 'revert to old datastream');
+
 
 // Hooks.
 define('ISLANDORA_VIEW_HOOK', 'islandora_view_object');
@@ -278,6 +280,16 @@ function islandora_menu() {
     'access arguments' => array(ISLANDORA_PURGE, 4),
     'load arguments' => array(2),
   );
+  $items['islandora/object/%islandora_object/datastream/%islandora_datastream/version/%/revert'] = array(
+    'title' => 'Revert to datastream version',
+    'page arguments' => array('islandora_revert_datastream_version_form', 4, 6),
+    'page callback' => 'drupal_get_form',
+    'file' => 'includes/datastream.version.inc',
+    'type' => MENU_CALLBACK,
+    'access callback' => 'islandora_datastream_access',
+    'access arguments' => array(ISLANDORA_REVERT_DATASTREAM, 4),
+    'load arguments' => array(2),
+  );
   $items['islandora/object/%islandora_object/datastream/%islandora_datastream/version/%/view'] = array(
     'title' => 'View datastream version',
     'page callback' => 'islandora_view_datastream',
@@ -402,6 +414,10 @@ function islandora_theme() {
       'file' => 'theme/theme.inc',
       'variables' => array('datastream' => NULL, 'version' => NULL),
     ),
+    'islandora_datastream_revert_link' => array(
+      'file' => 'theme/theme.inc',
+      'variables' => array('datastream' => NULL, 'version' => NULL),
+    ),
     'islandora_datastream_view_link' => array(
       'file' => 'theme/theme.inc',
       'variables' => array(
@@ -454,6 +470,10 @@ function islandora_permission() {
       'title' => t('View datastream history'),
       'description' => t('View all previous versions of a datastream.'),
     ),
+    ISLANDORA_REVERT_DATASTREAM => array(
+      'title' => t('Revert datastream history'),
+      'description' => t('Revert to a previous version of a datastream.'),
+    ),
   );
 }
 
diff --git a/tests/islandora_web_test_case.inc b/tests/islandora_web_test_case.inc
index baf7a8ee..be3b3b7e 100644
--- a/tests/islandora_web_test_case.inc
+++ b/tests/islandora_web_test_case.inc
@@ -168,16 +168,45 @@ class IslandoraWebTestCase extends DrupalWebTestCase {
     if (!is_object($object)) {
       $this->fail("Failed. Object passed in is invalid.", 'Islandora');
     }
-
-    foreach ($datastreams as $datastream) {
-      if (isset($object[$datastream])) {
-        $this->pass("Loaded datastream {$datastream} from PID {$object->id}.", 'Islandora');
-      }
-      else {
-        $this->fail("Failed to load datastream {$datastream} from PID {$object->id}.", 'Islandora');
+    else {
+      foreach ($datastreams as $datastream) {
+        if (isset($object[$datastream])) {
+          $this->pass("Loaded datastream {$datastream} from PID {$object->id}.", 'Islandora');
+        }
+        else {
+          $this->fail("Failed to load datastream {$datastream} from PID {$object->id}.", 'Islandora');
+        }
       }
     }
+  }
 
+  /**
+   * Asserts that an object's given datastreams are common-type image files.
+   *
+   * Uses PHPGD to run the assertion check. This means that only certain kinds
+   * of image files can be checked. Please check the documentation for the PHPGD
+   * imagecreatefromstring() function to determine what filetypes are valid.
+   *
+   * @param AbstractObject $object
+   *   The PID of the object.
+   * @param array $datastreams
+   *   An array of datastreams to check.
+   */
+  public function assertImageDatastreams($object, array $datastreams) {
+    if (!is_object($object)) {
+      $this->fail("Failed. Object passed in is invalid.", 'Islandora');
+    }
+    else {
+      foreach ($datastreams as $datastream) {
+        $datastream_string = $object[$datastream]->content;
+        if (!imagecreatefromstring($datastream_string)) {
+          $this->fail("Image datastream {$datastream} is either invalid or corrupt.", 'Islandora');
+        }
+        else {
+          $this->pass("Image datastream {$datastream} is valid.", 'Islandora');
+        }
+      }
+    }
   }
 
   /**
diff --git a/theme/theme.inc b/theme/theme.inc
index 10e1cd29..895ec8fe 100644
--- a/theme/theme.inc
+++ b/theme/theme.inc
@@ -339,6 +339,40 @@ function theme_islandora_datastream_delete_link(array $vars) {
   }
 }
 
+/**
+ * Renders a link to allow replacing of a datatream.
+ *
+ * @param array $vars
+ *   An array containing:
+ *   - datastream: An AbstractDatastream for which to generate a revert link.
+ *   - version: (optional) the version of the datastream to revert.
+ *
+ * @return string
+ *   Markup containing the url to delete a datastream, or empty if inaccessible.
+ */
+function theme_islandora_datastream_revert_link(array $vars) {
+  $datastream = $vars['datastream'];
+
+  $can_revert = islandora_datastream_access(ISLANDORA_REVERT_DATASTREAM, $datastream);
+
+  if ($vars['version'] !== NULL) {
+    if (count($datastream) == 1) {
+      $can_revert = FALSE;
+    }
+    $link = "islandora/object/{$datastream->parent->id}/datastream/{$datastream->id}/version/{$vars['version']}/revert";
+  }
+  else {
+    $can_revert = FALSE;
+  }
+
+  if ($can_revert) {
+    return l(t('revert'), $link);
+  }
+  else {
+    return '';
+  }
+}
+
 /**
  * Renders a link to allow editing of a datatream.
  *