Hello Richard,
The nested combo boxes work GREAT!  I followed the info at http://599cd.com/tips/access/two-combo-boxes/  It worked fine.  But then I went back and edited some of the data in the first combo box, and the selections in the remaining combo boxes would not change.  I needed to add the AfterUpdate refresh command. I have 4 nested combo boxes on my form. IT WORKS WONDERFULLY!  MANY THANKS!