Assign User to ES Group upon registration

Try to search the forums but can't find any answers.

Is it possible upon registration that users when selecting a custom field would automatically become a member in a ES group.

For example I have a list of schools. The users upon registration selects from that custom list and bsaed on their selection becomes a member of that group that is already created.

Specifically on registration they select from custom field University "Harvard University" and then upon complete registration become a member of "Harvard University" that was already created in ES groups.

Thanks!