diff --git a/libraries.api.php b/libraries.api.php
index a54b7b4..023cc0a 100644
--- a/libraries.api.php
+++ b/libraries.api.php
@@ -63,6 +63,27 @@
  *     - css: A list of CSS files to load, using the same syntax as Drupal
  *       core's hook_library().
  *     - php: A list of PHP files to load.
+ *   - dependencies: An array of libraries this library depends on. Similar to
+ *     declaring module dependencies, the dependency declaration may contain
+ *     information on the supported version. Examples of supported declarations:
+ *     @code
+ *     $libraries['dependencies'] = array(
+ *       // Load the 'example' library, regardless of the version available:
+ *       'example',
+ *       // Only load the 'example' library, if version 1.2 is available:
+ *       'example (1.2)',
+ *       // Only load a version later than 1.3-beta2 of the 'example' library:
+ *       'example (>1.3-beta2)'
+ *       // Only load a version equal to or later than 1.3-beta3:
+ *       'example (>=1.3-beta3)',
+ *       // Only load a version earlier than 1.5:
+ *       'example (<1.5)',
+ *       // Only load a version equal to or earlier than 1.4:
+ *       'example (<=1.4)',
+ *       // Combinations of the above are allowed as well:
+ *       'example (>=1.3-beta2, <1.5)',
+ *     );
+ *     @endcode
  *   - variants: (optional) An associative array of available library variants.
  *     For example, the top-level 'files' property may refer to a default
  *     variant that is compressed. If the library also ships with a minified and
diff --git a/libraries.module b/libraries.module
index c92bd01..d092079 100644
--- a/libraries.module
+++ b/libraries.module
@@ -262,6 +262,55 @@ function libraries_prepare_files(&$library, $version = NULL, $variant = NULL) {
 }
 
 /**
+ * Library post-detect callback to process and detect dependencies.
+ *
+ * It checks whether each of the dependencies of a library are installed and
+ * available in a compatible version.
+ *
+ * @param $library
+ *   An associative array of library information or a part of it, passed by
+ *   reference.
+ * @param $version
+ *   If the library information belongs to a specific version, the version
+ *   string. NULL otherwise.
+ * @param $variant
+ *   If the library information belongs to a specific variant, the variant name.
+ *   NULL otherwise.
+ *
+ * @see libraries_info()
+ * @see libraries_invoke()
+ */
+function libraries_detect_dependencies(&$library, $version = NULL, $variant = NULL) {
+  if (isset($library['dependencies'])) {
+    foreach ($library['dependencies'] as &$dependency_string) {
+      $dependency_info = drupal_parse_dependency($dependency_string);
+      $dependency = libraries_detect($dependency_info['name']);
+      if (!$dependency['installed']) {
+        $library['installed'] = FALSE;
+        $library['error'] = 'missing dependency';
+        $library['error message'] = t('The %dependency library, which the %library library depends on, is not installed.', array(
+          '%dependency' => $dependency['name'],
+          '%library' => $library['name'],
+        ));
+      }
+      elseif (drupal_check_incompatibility($dependency_info, $dependency['version'])) {
+        $library['installed'] = FALSE;
+        $library['error'] = 'incompatible dependency';
+        $library['error message'] = t('The version %dependency_version of the %dependency library is not compatible with the %library library.', array(
+          '%dependency_version' => $dependency['version'],
+          '%dependency' => $dependency['name'],
+          '%library' => $library['name'],
+        ));
+      }
+
+      // Remove the version string from the dependency, so libraries_load() can
+      // load the libraries directly.
+      $dependency_string = $dependency_info['name'];
+    }
+  }
+}
+
+/**
  * Returns information about registered libraries.
  *
  * The returned information is unprocessed, i.e. as registered by modules.
@@ -339,6 +388,7 @@ function libraries_info_defaults(&$library, $name) {
     'version callback' => 'libraries_get_version',
     'version arguments' => array(),
     'files' => array(),
+    'dependencies' => array(),
     'variants' => array(),
     'versions' => array(),
     'integration files' => array(),
@@ -352,7 +402,8 @@ function libraries_info_defaults(&$library, $name) {
   );
 
   // Add our own callbacks before any others.
-  $library['callbacks']['info'] = array_merge(array('libraries_prepare_files'), $library['callbacks']['info']);
+  array_unshift($library['callbacks']['info'], 'libraries_prepare_files');
+  array_unshift($library['callbacks']['post-detect'], 'libraries_detect_dependencies');
 
   return $library;
 }
@@ -538,6 +589,13 @@ function libraries_load($name, $variant = NULL) {
     // If the library (variant) is installed, load it.
     $library['loaded'] = FALSE;
     if ($library['installed']) {
+      // Load library dependencies.
+      if (isset($library['dependencies'])) {
+        foreach ($library['dependencies'] as $dependency) {
+          libraries_load($dependency);
+        }
+      }
+
       // Invoke callbacks in the 'load' group.
       libraries_invoke('load', $library);
 
diff --git a/tests/libraries.test b/tests/libraries.test
index 2a2e2cf..d88babc 100644
--- a/tests/libraries.test
+++ b/tests/libraries.test
@@ -50,6 +50,78 @@ class LibrariesTestCase extends DrupalWebTestCase {
     libraries_prepare_files($library, NULL, NULL);
     $this->assertEqual($expected, $library, 'libraries_prepare_files() works correctly.');
 
+    // Test libraries_detect_dependencies().
+    $library = array(
+      'name' => 'Library',
+      'dependencies' => array('example_missing'),
+    );
+    libraries_detect_dependencies($library);
+    $this->assertEqual($library['error'], 'missing dependency', 'libraries_detect_dependencies() detects missing dependency');
+    $error_message = t('The %dependency library, which the %library library depends on, is not installed.', array(
+      '%dependency' => 'Example missing',
+      '%library' => $library['name'],
+    ));
+    $this->verbose("Expected:<br>$error_message");
+    $this->verbose("Actual:<br>" . $library['error message']);
+    $this->assertEqual($library['error message'], $error_message, 'Correct error message for a missing dependency');
+    $version = '1.1';
+    $compatible = array(
+      '1.1',
+      '<=1.1',
+      '>=1.1',
+      '<1.2',
+      '<2.0',
+      '>1.0',
+      '>1.0-rc1',
+      '>1.0-beta2',
+      '>1.0-alpha3',
+      '>0.1',
+      '<1.2, >1.0',
+      '>0.1, <=1.1',
+    );
+    $incompatible = array(
+      '1.2',
+      '2.0',
+      '<1.1',
+      '>1.1',
+      '<=1.0',
+      '<=1.0-rc1',
+      '<=1.0-beta2',
+      '<=1.0-alpha3',
+      '>=1.2',
+      '<1.1, >0.9',
+      '>=0.1, <1.1',
+    );
+    $library = array(
+      'name' => 'Library',
+    );
+    foreach ($compatible as $version_string) {
+      $library['dependencies'][0] = "example_dependency ($version_string)";
+      // libraries_detect_dependencies() is a post-detect callback, so
+      // 'installed' is already set, when it is called. It sets the value to
+      // FALSE for missing or incompatible dependencies.
+      $library['installed'] = TRUE;
+      libraries_detect_dependencies($library);
+      $this->assertTrue($library['installed'], "libraries_detect_dependencies() detects compatible version string: '$version_string' is compatible with '$version'");
+    }
+    foreach ($incompatible as $version_string) {
+      $library['dependencies'][0] = "example_dependency ($version_string)";
+      $library['installed'] = TRUE;
+      unset($library['error'], $library['error message']);
+      libraries_detect_dependencies($library);
+      $this->assertEqual($library['error'], 'incompatible dependency', "libraries_detect_dependencies() detects incompatible version strings: '$version_string' is incompatible with '$version'");
+    }
+    // Instead of repeating this assertion for each version string, we just
+    // re-use the $library variable from the foreach loop.
+    $error_message = t('The version %dependency_version of the %dependency library is not compatible with the %library library.', array(
+      '%dependency_version' => $version,
+      '%dependency' => 'Example dependency',
+      '%library' => $library['name'],
+    ));
+    $this->verbose("Expected:<br>$error_message");
+    $this->verbose("Actual:<br>" . $library['error message']);
+    $this->assertEqual($library['error message'], $error_message, 'Correct error message for an incompatible dependency');
+
     // Test that library information is found correctly.
     $expected = array(
       'name' => 'Example files',
@@ -157,6 +229,20 @@ class LibrariesTestCase extends DrupalWebTestCase {
     $this->verbose('<pre>' . var_export($library, TRUE) . '</pre>');
     $this->assertEqual($library['variants']['example_variant']['installed'], TRUE, 'Existing variant found.');
 
+    // Test dependencies.
+    $library = libraries_load('example_dependency_missing');
+    $this->verbose('<pre>' . var_export($library, TRUE) . '</pre>');
+    $this->assertFalse($library['loaded'], 'Library with missing dependency cannot be loaded');
+    $library = libraries_load('example_dependency_incompatible');
+    $this->verbose('<pre>' . var_export($library, TRUE) . '</pre>');
+    $this->assertFalse($library['loaded'], 'Library with incompatible dependency cannot be loaded');
+    $library = libraries_load('example_dependency_compatible');
+    $this->verbose('<pre>' . var_export($library, TRUE) . '</pre>');
+    $this->assertEqual($library['loaded'], 1, 'Library with compatible dependency is loaded');
+    $loaded = &drupal_static('libraries_load');
+    $this->verbose('<pre>' . var_export($loaded, TRUE) . '</pre>');
+    $this->assertEqual($loaded['example_dependency']['loaded'], 1, 'Dependency library is also loaded');
+
     // Test the applying of callbacks.
     $expected = array(
       'name' => 'Example callback',
diff --git a/tests/libraries_test.module b/tests/libraries_test.module
index 4893b11..70f0fae 100644
--- a/tests/libraries_test.module
+++ b/tests/libraries_test.module
@@ -200,6 +200,38 @@ function libraries_test_libraries_info() {
     ),
   );
 
+  // Test dependency loading.
+  // We add one file to each library to be able to verify if it was loaded with
+  // libraries_load().
+  // This library acts as a dependency for the libraries below.
+  $libraries['example_dependency'] = array(
+    'name' => 'Example dependency',
+    'library path' => drupal_get_path('module', 'libraries') . '/tests/example',
+    'version' => '1.1',
+    'files' => array('js' => array('example_1.js')),
+  );
+  $libraries['example_dependency_missing'] = array(
+    'name' => 'Example dependency missing',
+    'library path' => drupal_get_path('module', 'libraries') . '/tests/example',
+    'version' => '1',
+    'dependencies' => array('example_missing'),
+    'files' => array('js' => array('example_1.js')),
+  );
+  $libraries['example_dependency_incompatible'] = array(
+    'name' => 'Example dependency incompatible',
+    'library path' => drupal_get_path('module', 'libraries') . '/tests/example',
+    'version' => '1',
+    'dependencies' => array('example_dependency (>1.1)'),
+    'files' => array('js' => array('example_1.js')),
+  );
+  $libraries['example_dependency_compatible'] = array(
+    'name' => 'Example dependency compatible',
+    'library path' => drupal_get_path('module', 'libraries') . '/tests/example',
+    'version' => '1',
+    'dependencies' => array('example_dependency (>=1.1)'),
+    'files' => array('js' => array('example_1.js')),
+  );
+
   // Test the applying of callbacks.
   $libraries['example_callback'] = array(
     'name' => 'Example callback',