>I'm using a textbox to collect a Date of Birth on a new record. The control source is a form variable that is initialized with a blank date {}. Is there a way to force the user to enter a complete 4 digit year rather than just a 2 digit year?

textbox.century=1

That will force the four-digit year. Now whether the user will use some of Fox's shortcuts, like typing just a two-digit year and assuming the rollover will kick in and fill the century, or omitting the year altogether and expecting Fox to use current year (which all works) - is something you may control, but I expect that may be a tad complicated. I'm fine with the behavior as is.