diff --git a/composer.drush.inc b/composer.drush.inc
index 10855cc..a3b0002 100644
--- a/composer.drush.inc
+++ b/composer.drush.inc
@@ -50,3 +50,22 @@ function drush_composer($command = '') {
     drush_log(dt('Composer was not installed correctly.'), 'error');
   }
 }
+
+/**
+ * Implementation of hook_drush_pm_post_download().
+ */
+function composer_drush_pm_post_download($project, $release) {
+  // Check if there's a composer.json to process.
+  if (file_exists($project['full_project_path'] . '/composer.json')) {
+    // Composer uses the current working directory, so we'll mock it as the
+    // path as the current working directory.
+    $originalPath = getcwd();
+    chdir($project['full_project_path']);
+
+    // Process the file.
+    drush_composer('install');
+
+    // Switch back to the original file path.
+    chdir($originalPath);
+  }
+}