| Abbreviation | Definition |
|---|---|
| ISLA | International Securities Lending Association |
| ISLA | International Surf Lifesaving Association |
| ISMA | Indiana State Medical Association |
| ISMA | International Seal Manufacturers Association |
| ISMA | International Security Management Association |
| ISMA | International Snowmobile Manufacturers Association |
| ISMA | International Social Marketing Association |
| ISMA | International Social Media Association |
| ISNA | Irish Specialist Nurseries Association |
| ISOA | Indiana SWAT Officers Association |
| ISOA | Ingham School Officers Association |
| ISOA | International Stability Operations Association |
| ISOA | International Sunflower Oil Association |
| ISOA | International Sunflower Oils Association |
| ISPA | Illinois School Psychologists Association |
| ISPA | International School Psychology Association |
| ISPA | International Segway Polo Association |
| ISPA | International Sleep Products Association |
| ISPA | Iowa School Psychologists Association |
| ISRA | Indiana Street Rod Association |