| Abbreviation | Definition |
|---|---|
| ANZA | Australian and New Zealand Association |
| ANZSLA | Australian and New Zealand Sports Law Association Inc |
| AO2CA | Airline Oxygen Council of America |
| AOA | Alaska Optometric Association |
| AOA | Auxiliary Organizations Association |
| AOB | Angels Of Blind |
| AOC | American Oceans Campaign |
| AOF | Ancient Order of Foresters |
| AOJS | Association of Orthodox Jewish Scientists |
| AOS | American Osler Society |
| AOU | American Ornithological Union |
| AP | Animal Programs |
| AP | Antarctica Project |
| APA | Aborigines Progressive Association |
| APA | Association of Parents of Addicts |
| APAC | Aging Program Advisory Committee |
| APAC | Asian-Pacific American Council |
| APACHE | Association of Peoria Area Christian Home Educators |
| APAF | American Pharmaceutical Association Foundation |
| APALCSC | Asian Pacific American Legal Center of Southern California |