| MSSC | Madison Sports and Social Club 
| Others |
| MSSC | Mahomet Seymour Soccer Club
| Others |
| MSSC | Malaysian School Sports Council
| Others |
| MSSC | Manayunk Sport And Social Club
| Others |
| MSSC | Manayunk Sport and Social Club's
| Others |
| MSSC | Manila Shared Services Center
| Others |
| MSSC | Manufacturing Skill Standard Council
| Others |
| MSSC | Manufacturing Skill Standards Council
| Others |
| MSSC | Manufacturing Skills Standards Council
| Others |
| MSSC | Marine Society and Sea Cadets
| Others |
| MSSC | Maritime Safety and Security Center
| Others |
| MSSC | Marking Stenciling Sealing and Coding
| Others |
| MSSC | Martin Six String Customs
| Others |
| MSSC | Maryland Suburban Swim Club
| Others |
| MSSC | Math and Science Skills Center
| Others |
| MSSC | Medical Society of Sedgwick County
| Others |
| MSSC | Medieval Studies Student Colloquium
| Others |
| MSSC | Michigan Student Sustainability Coalition
| Others |
| MSSC | Microscopic Society of Southern California
| Others |
| MSSC | Microsoft Site Server Commerce
| Others |
| MSSC | Microsoft Solutions for Security and Compliance
| Others |
| MSSC | Military Student Success Center
| Others |
| MSSC | Millennium Scholastic School & College
| Others |
| MSSC | Mineralogical Society of Southern California
| Others |
| MSSC | Mississauga Sport and Social Club
| Others |
| MSSC | Mississippi Safe Schools Coalition
| Others |
| MSSC | Modified Suzuki Swift Club
| Others |
| MSSC | Molinara Sports Social Club
| Others |
| MSSC | Montana Safety Services Council
| Others |
| MSSC | Multi State Salinity Coalition
| Others |
| MSSC | Multiband Switch and Service Configuration
| Others |
| MSSC | Multicultural Student Services Center
| Others |
| MSSC | Muscle Shoals Sailing Club
| Others |