| Abbreviation | Definition |
|---|---|
| AARG | Arizona Adventure Riding Group |
| AARP | Aged Adults Riding Proud |
| ABB | American Bucking Bull |
| ABRS | Authority of British Riding Schools |
| ACTRA | Atlantic Canada Trail Riding Association |
| ADA | Alamo Dressage Association |
| AIRC | Association of Irish Riding Clubs |
| AJC | Australian Jockey Club |
| ALRC | Alta Loma Riding Club |
| ANRC | American National Riding Commission |
| AOER | Archers of East Riding |
| APRA | American Professional Rodeo Association |
| ARAS | Advanced Riding Assistance System |
| ASHA | American Saddlebred Horse Association |
| ATHRA | Australian Trail Horse Riders Association |
| ATRC | American Therapeutic Riding Center |
| ATRO | Acadiana Therapeutic Riding Organization |
| AWARE | Always Wanted A Riding Experience |
| BB | BareBack (horse riding) |
| BCHBC | Back Country Horsemen of British Columbia (Canada) |