well a field by itself only has a control source,
but I'm assuming you mean a combo box, and yes it is possible heres an example:
In a combo box I have the control source set to "Manager" so it will save the information to the manager field in whatever table that field came from,
however for record source you could say:
SELECT DISTINCTROW [Project Manager Query].managerlastname; or something like that(all that stuff just means I got it from a query)
HTH, reply if you need more clarification
Rpb