I need to formulate a query for a combo box that takes into account the value in a yes/no checkbox that is on the same form. I would like to write a conditional "where", conditional on the value of the checkbox. If the checkbox is Yes, I want to use one where condition; if the box is No I want to use a different where condition.

Do you mean basing the rowsource of the combo box on whether or not the checkbox is checked?

Yes, the query in the rowsource of the combo box.

Place some code in the After Update event of the combo box that alters the rowsource property of the combo box. Something like:If Me.chkBox Then
Me.combo.Rowsource="SELECT Name FROM tbl WHERE Active=True;"
Else
Me.combo.Rowsource="SELECT Name FROM tbl WHERE Active=False;"
End If

Many thanks. It seems obvious -- once someone tells you how.