The American Kennel Club registers purebred dogs within the United States, while the United Kennel Club registers purebred dogs within the United States and 25 other countries. The AKC focuses on breed conformity and genetics, while the UKC examines performance of working and breed purity.

The AKC, established in 1884, is the older of the two registries and is, unlike the UKC, a nonprofit organization. The AKC specializes in conformation shows, where individual dogs are evaluated for conformance to breed traits. All breeds recognized by the organization are eligible for these competitions. Performance shows are less common, and limited breeds, mostly sporting and hunting breeds, are represented. The organization also sponsors canine companion competitions, which focus on obedience, tracking and agility. Professional dog handlers are allowed in AKC competitions.

In contrast to the AKC, the UKC recognizes all purebreds, including the American Pit Bull. The organization rarely sponsors conformation competitions except in conjunction with performance trials. Like the AKC, the UKC registers purebreds for pedigree, but the organization also keeps a separate registry, containing both purebred and mix-breed dogs, that lists dogs by performance. These animals are eligible to compete in all UKC trials and junior showmanship events. The UKC does not allow professional handlers at its events.