| AAACS | Average Amino Acid Conservation Score | |
| AACD | Alabama Association of Conservation Districts | |
| AACD | Arizona Association of Conservation Districts | |
| ABCA | Ausable Bayfield Conservation Authority | |
| ABEC | Animal Behavior Ecology and Conservation | |
| ACAD | Avian Conservation Assessment Database | |
| ACAP | Agreement on the Conservation of Albatrosses and Petrels | |
| ACBK | Association for the Conservation of Biodiversity of Kazakhstan | |
| ACC | American Conservation Coalition | |
| ACCB | Angkor Centre for Conservation of Biodiversity | |
| ACCB | African Congress for Conservation Biology | |
| ACCB | Allamakee County Conservation Board | |
| ACCB | Audubon County Conservation Board | |
| ACCD | Allegheny County Conservation District | |
| ACCI | Ape Cognition and Conservation Initiative | |
| ACCR | Advisory Committee for Conservation and Restoration | |
| ACCRU | Alberta Cooperative Conservation Research Unit | |
| ACCS | Alaska Center for Conservation Science | |
| ACE | American Conservation Experience | |
| ACPF | Agriculture Conservation Planning Framework | |
| ACPU | Advanced Conservation and Protection Unit | |
| ACRN | Animal Conservation Rehabilitation Network | |
| ACSFP | Alcoa Conservation and Sustainability Fellowship Program | |
| ACTN | African Conservation Tillage Network | |
| AFCD | Agriculture, Fisheries and Conservation Department | |
