Thanks for the replies.
I don't think I have the roles confused, but what I was showing you above is that I have a sub that works BY ITSELF. It properly looks up and finds the dept from an external worksheet. If you paste that SUB into a module, and run it, it will work. You are correct in that the way I show it above, it does not accept any arguments. When I try to use it with the FUNCTION (and then, yes, I have to modify it to accept a UID parameter), it doesn't work. Heck, even if I don't pass it anything and hardcode the UID like it shows above, it quits working when I call it with the FUNCTION, which is strange to me. I want a function because I want to type "=GET_Dept(A12)" in a cell and have it go look up that UID in my external spreadsheet without having to copy paste stuff around.