diff --git a/src/Check/Callback.php b/src/Check/Callback.php
index <HASH>..<HASH> 100644
--- a/src/Check/Callback.php
+++ b/src/Check/Callback.php
@@ -6,6 +6,13 @@ class Callback extends \Psecio\Validation\Check
 {
     public function execute($input)
     {
-        return false;
+        $addl = $this->get();
+        list($class, $method) = explode('::', $addl[0]);
+        
+        if (!method_exists($class, $method)) {
+            throw new \InvalidArgumentException('Invalid callback: '.$method);
+        }
+        $call = $class.'::'.$method;
+        return $call($input);
     }
 }
making the Callback check work with a static class::method