| Acronym | Meaning |
| OCA | Obligation Cost Authority |
| OCA | Obstacle Clearance Altitude |
| OCA | Offensive Counter Air |
| OCA | Office of Chief Architect (GSA) |
| OCA | Office of Community Affairs (law enforcement) |
| OCA | Office of Compliance Analytics (US IRS) |
| OCA | Office of Compliance and Assessment (US Navy) |
| OCA | Office of Consumer Advocate (Pennsylvania) |
| OCA | Office of Consumer Affairs |
| OCA | Office of Court Administration |
| OCA | Office of Cultural Affairs (New Mexico, USA) |
| OCA | Office of the City Attorney (various locations) |
| OCA | Office of the Court Administrator |
| OCA | Older Coloradans Act |
| OCA | Ontario Court of Appeal (Canada) |
| OCA | Open Continuous Announcement (government jobs) |
| OCA | Operating Cost Authority |
| OCA | Operational Capability Area (GIG IA architecture version 1.1) |
| OCA | Operational Command Authority |
| OCA | Operational Condition Assessment (US Army Corps of Engineers) |
| OCA | Operational Control Authority |
| OCA | Organized Crime Agency of British Columbia (Canada) |
| OCA | Original Classification/Classifying Authority |
| OCA | Original Controlling Authority |
| OCA | Originating Case Agency |
| OCA | Overlapping Claim Area |
| OCA | Owner Controlled Area |
| OCA | Oxygen Compatibility Assessment (US NASA) |