| 4Winds Tours - http://www.4windstours.com/ Ooffers cycling, barging, spring flower, and brewery tours in Holland and France as well as hiking/biking tours in Austria, Ireland, and Denmark. |
| Academic Tours - http://www.academictours.com/ |
| Action Factory - http://www.actionfactory.com/ |
| Adelanta Travel Services - http://www.adelanta.co.uk/ Customised group tours of Great Britain (UK) and Western Europe. |
| ADVENT Tours - http://www.advent-tours.com/ Offers a range of subject-based educational tours covering topics such as English, arts, geography, history, languages, and drama. |
| Adventures on Skis - http://www.adventuresonskis.com/ Offers skiing, biking, hiking, equestrian, and other outdoor vacations in the Alps, Europe, South America, and the Rockies. |
| Agency Plus - http://www.agency.hu/ |
| Alpin Travel - http://www.alpintravel.ch/ Offers heli-ski and heli-snowboard packages at the Gudauri Caucasus, Republic of Georgia. |
| Alpine Adventure Tours - http://www.alpineadventuretours.com/ Offers cycling tours in France and Italy and cross-country ski tours in Europe. |
| Alpine Interface - http://www.alpineinterface.com/ Offers trekking and hiking in the Alps, walking tours in Provence, adventure trekking in Nepal, and sea kayaking in Mexico. |
| Alternative Holidays - http://www.alternative-holidays.com/ Lesbian and gay travel company offering an array of vacation packages. |
| Altius - http://www.altius.pl/ Offers outdoor adventures including horse riding, rock climbing, hiking in the Alps, skiing, and paragliding. |
| American Tours & Travel, Inc. - http://www.travelgroups.com/ Specializes in student group travel throughout the U.S., Mexico, and Europe. |
| Anglia Battlefield Tours - http://www.angliabattlefields.co.uk/ Offers battlefield and pilgrimage tours in Britain and Europe for schools, colleges, and the general public. |
| Any Mountain Tours - http://www.anymtn.com/ Offers ski vacation and theme packages throughout the western U.S. and Canada. |
| Arc Boutant - http://www.arcboutant.org/ Offers a summer program in architectural restoration and historic preservation in Europe. Students live and work on-site. |
| Archetours, Inc. - http://www.archetours.com/ |
| Art of Travel - http://www.art-of-travel.com/ Offers a variety of international and domestic tours, including guided visits through artistic and architectural landmarks. |
| ATG Oxford - http://www.atg-oxford.co.uk/ Offers a range of walking and cycling tours and special interest holidays in Europe and further afield. |
| Atlantik Tours - http://www.atlantik.is/ Offers circle tours, shore excursions, incentive travel in Iceland and daytours to Greenland. |