| Abbreviation | Definition |
|---|---|
| IIIT | International Institute of Islamic Thought |
| IIL | Institute for Information Literacy |
| IIMD | International Institute of Metropolitan Detroit |
| IIRC | Image and Identity Research Collective |
| IIRR | International Institute of Rural Reconstruction |
| IIS | Infinity International Society |
| IISC | Indian Institute of Science |
| IISC | Interaction Institute for Social Change |
| IISC | International Institute of Space Commerce (Isle of Man) |
| IISD | International Institute for Sustainable Development |
| IISTE | International Institute for Science, Technology, and Education |
| IITC | International Indian Treaty Council |
| IIVS | Institute for In Vitro Sciences |
| IJR | Institute for Justice and Reconciliation |
| IJWO | Iranian Jewish Women Organization |
| ILAE | International League Against Epilepsy |
| ILCA | International Lactation Consultant Association |
| ILGA | International Lesbian and Gay Association |
| ILN | International Literacy Network |
| ILRC | Immigrant Legal Resource Center |