Student and educational travel agencies,United states of america

http://www.acis.com/
offices located in atlanta atlanta,boston,chicago,houston and sacramento

http://www.adventurescrosscountry.com/

http://www.adventuresuenttravel.com/
educational tours all over USA

http://www.eftours.com/
over 300 student and educational tours
located in cambridge,massacheutts

http://www.exploritas.org/
search by theme

global travel alliance

http://www.holbrooktravel.com/
latin america and africa

http://www.pacificdiscovery.org/ ,maine
does southeast asia,tibet,ecuador,new zealand,australia and papua new guinea

http://smithsonianjourneys.org/

http://www.studenttraveler.com/ is possibly usa based
also produces a magazine called student traveller