I have a Main form that includes a couple of subforms. When the user enters a specific key number I would like the description of the key to automatically be filled in.

I have a separate table created that holds the information of the key number and the description to the specific key number. Some key numbers may have more than one description and would be ok if if these desciptions were visible for the user to choose from.

Normally I would suggest that you have only one description per key number using the key number like a unique ID but I think you are looking for some flexibility in choosing the description after the initial key selection in which case set up a combo box with the choices of description for each key number. You haven't explained much about the layout but you could set up an On Click Event to run a query which asks you to enter a key number each time which then brings up the combo box for you to make a final choice.

HTH