>Holy cow! It works now. I knew I did something incorrectly. Thank you very much. This will go a long way to what I am trying to do: An admin task to shutdown all instances of our application and verifying that it is indeed closed.

You're welcome. Glad to be of help.
>
>>I was going to ask to see the declaration.< s > I think that's the problem. Try changing the declaration and passing it by value rather than reference as below

DECLARE INTEGER IsWindow IN User32;
>>  INTEGER hWnd
>>? IsWindow(_VFP.hwnd)