| AAAA | American Association of Advertising Agencies | |
| AAAAM | Area Agencies on Aging Association of Michigan | |
| AAAAM | Area Agencies on Aging Associate Member | |
| AAAJ | Advertising Agencies Association of Jamaica | |
| AAAL | Area Agency on Aging for Lincolnland | |
| AAAP | Art Agency And Production | |
| AACBS | Association to Advance Collegiate Schools of Business (accrediting agency) | |
| AAG | Associated Agency Group | |
| AAI | All Agency Inventory | |
| AAISA | Alberta Association of Immigrant Serving Agencies | |
| AAM | All Agency Memos | |
| AAOA | Area Agency On Aging | |
| AAPA | Advertising Agency Production Association | |
| AARA | Addis Ababa Revenue Agency | |
| AASA | Aging Adult Services Agency | |
| AASC | Appalachian Agency For Senior Citizens | |
| ABAD | Agency for Barani Area Development | |
| ABEA | Association of Bulgarian Energy Agencies | |
| ABIA | Association of British Introduction Agencies | |
| ABK | AKB Landscaping Gardening & Property Management | |
| ABLA | Andrea Brown Literary Agency | |
| ABMA | Army Ballistic Missile Agency | |
| ABNA | Ahlul Bayt News Agency | |
| ABVR | Agency Based Voter Registration | |
| ACAU | A Child Among Us (international child adoption agency) | |
