| 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) |