| ISSF | Ibm Software Services for Federal 
| Others |
| ISSF | Independent Schools of South Florida
| Others |
| ISSF | Input Signal Step Function
| Others |
| ISSF | Institutional Strategic Support Fund
| Others |
| ISSF | International Seafood Sustainability Foundation
| Others |
| ISSF | International Shooting Sport Federation
| Others |
| ISSF | International Shooting Sports Federation
| Others |
| ISSF | International Space Safety Foundation
| Others |
| ISSF | International Stainless Steel Forum
| Others |
| ISSF | International Student Science Fair
| Others |
| ISSF | International Student Subsidy Fund
| Others |
| ISSF | International Symposium on Stratified Flows
| Others |
| ISSF | Islamic Solidarity Sports Federation
| Others |