| Asociaci Argentina Amigos de la Astronom | Academic & Science |
| American Academy of Anesthesiologist Assistants | Academic & Science |
| Asociación Argentina Amigos de la Astronomía | Academic & Science |
| Asian Academic Accounting Association | Accounts and Finance |
| American Association for Advertising Agencies | Business |
| Association of Accredited Advertising Agents | Business |
| Ann Arbor Administrators Association | Business |
| Antique Advertising Association of America | Business |
| Alamo Area Aquatic Association | Community |
| American Academy of Adoption Attorneys | Community |
| Albuquerque Aerostat Ascension Association | Community |
| Alexandria Area Arts Association | Community |
| American Association for Affirmative Action | Community |
| American Association of Aardvark Aficionados | Community |
| Associated Actors and Artists of America | Community |
| Antics of Alice And Andy | Community |
| Arizona Asian American Association | Community |
| Action Against Ageing Association | Community |
| Asians Are Awesome Association | Community |
| American Association of Advertising Agencies | Community |
| Alps Adria Acoustics Association | Community |
| American Association for the Advancement of Atheism | Community |
| American Association Against Acronyms | Community |
| Association Against Acronym Abuse | Community |
| Atlanta Area Aquarium Association | Community |
| Academics Activities Assembly Advisory | Computing |
| Authentication, Authorization, Auditing, and Accounting | Computing |
| Amicale Amateurs Automobiles Antiques | General |
| Association Amie de l'Automobile Ancienne | General |
| Asociacion Amigos Autos Antiguos | General |
| Autonomous Arthropod Aerial Appliance | General |
| AAA Army Aviation Association | General |
| Albania Alemania Andorra Angola | General |
| Acronym Acronym Acronym Acronym | General |
| anyway Awesomely Atrocious Arrogant | General |
| Addis Ababa Action Agenda | General |
| Always Accessible Always Afloat | General |
| Americans Against Acronym Abuse | General |
| Alberta Aerial Applicators Association | General |
| Affiliated Americans Against Acronyms | General |
| Always Afloat Always Accessible | General |
| Associated Actors and Artistes of America | General |
| Atelier Autodidacts Anti Algorithms | General |
| Alava Albacete Alicante Almeria | General |
| Alabama Accumulated Adjustment Account | General |
| Alcoholics Anonymous of Atheist and Agnostics | General |
| Amicale Azureenne des Amateurs d'Alpine | General |
| Association Annoneenne Automobiles Anciennes | General |
| Australian Automotive Aftermarket Association | Governmental |
| Authentication Authorization Accounting And Auditing | Governmental |
| Asian Amateur Athletics Association | International |
| Association for Applied Animal Andrology | Medical |
| Army Aviation Association of America | Military and Defence |
| Alabama Alaska Arizona Arkansas | Regional |
| African American Alumni Association | Regional |
| Australian Association of Advertising Agencies | Regional |
| Athleticism Attitude Academics and Adversity | Sports |
| Anguilla Amateur Athletic Association | Sports |
| Amateur Athletic Association of America | Sports |
