ACPA
- 4,4'-Azobis(4-cyanopentanoic acid)
- Aboriginal Centre for the Performing Arts
- Air Canada Pilots Association
- Allegheny County Port Authority
- American Catholic Philosophical Association
- American China Policy Association
- American College Personnel Association
- Anti-citrullinated protein antibody
- Anticybersquatting Consumer Protection Act
- Arachidonylcyclopropylamide
- Armenian College and Philanthropic Academy
- Association of Certified Public Accountants