| Abbreviation | Definition |
|---|---|
| INPA | International Newborn Photography Association |
| INSA | International Naples Sabot Association |
| INSA | National Shipowners Association |
| INTA | International Nail Technicians Association |
| INTA | Irish National Taekwon Do Association |
| IOA | Indian Olympic Association |
| IOA | International Ombudsman Association |
| IOA | International Osteopathic Association |
| IOA | International Ostomy Association |
| IOA | International Ozone Association |
| IOEB | International Osteopathy Examining Board |
| IOPA | Islands Organic Producers Association |
| IORA | Indian Ocean Rim Association |
| IOSA | Indiana Orff Schulwerk Association |
| IOSA | Islands Oil Spill Association |
| IOSA | Islands' Oil Spill Association |
| IOTA | Indiana Occupational Therapy Association |
| IPA | Illinois Principals Association |
| IPA | Indiana Percussion Association |
| IPA | Indonesian Petroleum Association |