| International Astronomical Youth Camp | IAYC |
| International Auxiliary Language Association | International Auxiliary Language Association |
| International Bank Account Number | International Bank Account Number |
| International Biathlon Union | Internationale Biathlon Union |
| International Color Consortium | International Color Consortium |
| International Council for Science | Internationaler Wissenschaftsrat |
| International Council of Museums | International Council of Museums |
| International Council on Monuments and Sites | International Council on Monuments and Sites |
| International Earth Rotation and Reference Systems Service | Internationaler Erdrotationsdienst |
| International English Language Testing System | International English Language Testing System |
| International Federation of Library Associations and Institutions | IFLA |
| International gamers award | International Gamers Award |
| International Linear Collider | International Linear Collider |
| International Mobile Equipment Identity | International Mobile Equipment Identity |
| International Music Score Library Project | International Music Score Library Project |
| International Phonetic Association | International Phonetic Association |
| International Physicians for the Prevention of Nuclear War | International Physicians for the Prevention of Nuclear War |
| International protection | Schutzart |
| International Rugby Board Hall of Fame | IRB Hall of Fame |
| International Rugby Hall of Fame | International Rugby Hall of Fame |
| International Security Assistance Force | ISAF |
| International Tennis Hall of Fame | International Tennis Hall of Fame |
| International Union of Socialist Youth | International Union of Socialist Youth |
