| Abbreviation | Definition |
|---|---|
| IRGS | International Relations Graduate Schools |
| IRHS | Indian River High School |
| IRHS | Ironwood Ridge High School |
| IRHS | Iroquois Ridge High School |
| IRMS | Icicle River Middle School |
| IRMS | Indian Ridge Middle School |
| IRMS | Indian River Middle School |
| IRNAA | Industrial Roosevelt National Alumni Association |
| IRSB | Independent Review of the School Based |
| IRSD | Indian River School District |
| IRSHDC | Indian Residential School History & Dialogue Centre |
| IRSI | Indian Residential School Initiative |
| IRSSA | Indian Residential School Settlement Agreement |
| ISA | International School of the Americas |
| ISA | International Schools Assessment |
| ISA | Internationals Schools Assessment |
| ISAAC | Interdistrict School for Arts And Communication |
| ISAC | Independent Schools Adventure Cruises |
| ISAK | International School of Asia Karuizawa |
| ISAL | IASA School for Advanced Leadership |