| Inter Society Coordinating Committee | Academic & Science |
| International Sustainability Carbon Certification | Business |
| International Sustainability and Carbon Certification | Business |
| Indiana Statistical Consulting Center | Business |
| International Staffing Consulting Co | Business |
| Independent Schools Compensation Corporation | Business |
| International Securities Clearing Corporation | Business |
| Indian Spring Country Club | Community |
| Inverness South Community Council | Community |
| IEEE Symposium on Computers and Communications | Community |
| International Solar Cookers Conference | Community |
| International Skin Carcinogenesis Conference | Community |
| Illinois Skyway Collegiate Conference | Community |
| International Stereo Club Competition | Community |
| Information Systems Coordination Committee | Computing |
| Initial System Capability Configuration | Computing |
| Intelligent Systems Control Console | Computing |
| Internet Security Courseware Consortium | Computing |
| Isuzu Sports Car Club | General |
| International Sports Car Club | General |
| Intestinal Stem Cell Consortium | General |
| Integrated Solar Combined Cycle | General |
| inno Screen Capture Codec | General |
| Idaho State Correctional Center | General |
| International Sports Chamber of Commerce | Governmental |
| Invasive Species Council of California | Governmental |
| Inter-Society Color Council | Governmental |
| India Supply Chain Council | Governmental |
| International Symposium on Capillary Chromatography | International |
| International Symposium on Coal Combustion | International |
| International Society for Children with Cancer | Medical |
| Implementation Science Consortium in Cancer | Medical |
| Islamic Supreme Council of Canada | Regional |
| Islamic Society of Chester County | Regional |
| International Skating Center of Connecticut | Sports |
