IHSA
| Acronym | Definition |
|---|---|
| IHSA | Illinois High School Association |
| IHSA | Intercollegiate Horse Show Association |
| IHSA | Illinois Head Start Association (est. 1978) |
| IHSA | Institut Hukum Sumberdaya Alam (Indonesian: Natural Resources Law Institute; Jakarta, Indonesia) |
| IHSA | Iowa Head Start Association (Lamoni, IA) |
| IHSA | Industrial Hygiene Student Association (industrial health education and research student group; various universities) |