| OPSA | Association for Office Professionals of South Africa 
| Others |
| OPSA | Oak Park String Academy
| Others |
| OPSA | Office of Professional School Advising
| Others |
| OPSA | Office of Program and Strategic Analysis
| Others |
| OPSA | Office of Public Safety Accountability
| Others |
| OPSA | Office of the Parking Summons Advocate
| Others |
| OPSA | Office of the Pohnpei State Auditor
| Others |
| OPSA | Office Professionals of South Africa
| Others |
| OPSA | Oklahoma Political Science Association
| Others |
| OPSA | Oklahoma Private School Association
| Others |
| OPSA | Olongapo Practical Shooters Assn
| Others |
| OPSA | Omaha Pet Sitters Association
| Others |
| OPSA | Operating Plant Service Agreement
| Others |
| OPSA | Oregon Public Safety Academy
| Others |
| OPSA | OSSTMM Professional Security Analyst
| Others |
| OPSA | Otago Polytechnic Students Association
| Others |
| OPSA | Otago Polytechnic Students' Association
| Others |
| OPSA | Otero Practical Shooting Association
| Others |
| OPSA | Ovarian Papillary Serous Adenocarcinoma
| Others |
| OPSA | Overseas Plastic Surgery Appeal
| Others |
| OPSA | Owens Park Students Association
| Others |