| ISSSC | Independent Schools Skiing and Snowboarding Championships 
| Others |
| ISSSC | Institute for the Study of Secularism in Society and Culture
| Others |
| ISSSC | International Seppala Siberian Sleddog Club
| Others |
| ISSSC | International Society for Six Sigma Certifications
| Others |
| ISSSC | International Society for the Suppression of Savage Customs
| Others |
| ISSSC | International Summer School on Smart Cars
| Others |
| ISSSC | Irish Special Schools Sports Council
| Others |