Brian, Thank you for the tip - it worked well and was just what I needed.

The reason I did not use categories is that I had tagged some contacts with
the category "Friends" and the others in the folder were tagged the category
"Family". I then viewed by categories. So far so good. There was one group
of Friends and one group of Family. However, when I clicked on any of the
column headers to change the sort order, the view changed and all the
contacts were no longer grouped.

If seems that when I group by any field except categories, I can click on
the column headers to change the sort order and the groups are still there.
With categories as the grouping field, clicking on the column headers
eliminates the grouping.

Thank you for your feedback.