| Abbreviation | Definition |
|---|---|
| IRDC | International Rally Drivers Club |
| IRFC | Indian Railways Fan Club |
| IRFC | Indian River Flying Club |
| IRGC | Irvine Ravenspark Golf Club |
| IRPC | Indianhead Rifle and Pistol Club |
| IRRC | Indiana Road Runners Club |
| IRWC | Indian River Woodcarvers Club |
| ISC | Internet Scrabble Club |
| ISCA | Inline Skating Club of America |
| ISCA | Irish Setter Club of America |
| ISCL | Ice Skating Club Louviers |
| ISCR | International Sporting Club de la Rague |
| ISCW | Irish Setter Club of Wales |
| ISDC | Irish Subaru Drivers Club |
| ISFC | Indiana Southwest Futbol Club |
| ISFC | Irina Slutskaya Fan Club |
| ISSCA | Impala SS Clubs of America |
| ISSSC | International Seppala Siberian Sleddog Club |
| ITCA | Irish Terrier Club of America |
| ITCC | International Tea Cuppers Club |