| POSSE | Party Of Sixth Seventh And Eighth 
| Others |
| POSSE | Peers Organized to Support Student Excellence
| Others |
| POSSE | Plan Organize Study Schedule and Evaluate
| Others |
| POSSE | Pluto And Outer Solar System Explorer
| Others |
| POSSE | Portland Open Source Software Entrepreneurs
| Others |
| POSSE | Preparing Outstanding Scholars for Special Education
| Others |
| POSSE | Preserve Our Student Shows For Eternity
| Others |
| POSSE | Program of Ship Salvage Engineering
| Others |
| POSSE | Publish on your Own Site Syndicate Elsewhere
| Others |