The American Staffordshire Terrier is a breed of dog. The breed is a relative of the American Pit Bull Terrier. Early Bulldog–Terrier crosses were brought to the US with the British and Irish settlers, especially after the Civil War, where they were mainly used as fighting dogs, but also as hunting dogs and farm and guard dogs.

In the early 1830s animal fights, especially the formerly extremely popular bull-baiting and bearbaiting (the roots of which go back to the old Roman arenas) became illegal in old Britain and Ireland, after the Human Ethics Act passed. From then on the people began to organize ratfights and dogfights, because they were much easier to hide from the officials than fights with big game like bulls. At first, little terrier strains were used in the rat- and dog-fights, such as the old white English terrier and its black and tan cousin, today known as the Manchester Terrier, which were known for their extreme prey drive and gameness. Some of these dogs were crossed with bulldogs, to create a breed which retained the abilities of the terriers, but with the strength and jaw grip of the bulldogs.

Responsible owners and breeders provide American Staffordshire Terriers with humane, responsible ownership, often training these dogs for community service tasks such as pet therapy and search and rescue. There are also 'Amstaff' charitable organizations that rescue and rehabilitate abused, abandoned, or stray dogs, placing them into foster or adoptive homes. American Staffordshire Terriers were first recognized by the American Kennel Club in 1936. They are a member of the Terrier and Molosser groups.

Appearance
The American Staffordshire Terrier is a medium-sized dog that ranges from 40 to 50 cm (17 to 20 inches) at the withers, and weighs from 26 to 30 kg (50 to 70 pounds).

The dog is of square build, and gives the impression of great strength, agility, and grace for their size. They should be stocky, not long-legged or racy in outline. The chest is deep and broad, but should not be too wide. The neck should be strong, and well arched.

The coat is short and glossy. Any color, solid, partial, or patched is permissible, but all white, more than 80 per cent white, black and tan, and liver are not to be encouraged.

Temperament
These dogs should be courageous, tenacious, friendly, extremely attentive, and extraordinarily devoted. Bred to be extremely friendly towards humans, American Staffordshire Terriers are not natural guard dogs. An overly protective and/or aggressive behavior, accompanied by fearlessness, is generally a bad sign. These dogs are good with children and owners, can sometimes get along with other dogs, cats and any other animal if raised properly and introduced through puppy years. They can be aggressive if not socialized properly.

These dogs learn quickly from the subtlest of our behaviors. They are thus not only highly responsive during training, but also pick up good habits, such as house training. This can become a problem when an owner unknowingly allows the dog to pick up bad behaviors. A typical training regimen should begin at 8 to 10 weeks of age. It has been proven that Positive Reinforcement Training works very well with this breed.

The American Staffordshire Terrier is a loyal companion dog. He also requires a very large amount of time for rough, or hard working play. Weight pulling, and agility training are what he favors most. He likes to run, but with a proper harness, he loves to pull a skateboard or rollerblading kid. A pull rope hung from a tree encourages self motivating play, but your AmStaff type breed really wants to enjoy playtime with you and the kids.

Similarities to other Bull Terriers
The American Staffordshire Terrier and the American Pit Bull Terrier are closely related breeds, sharing a common ancestry as recently as the 1960s when the Staffordshire Terrier Studbook was re-opened and then closed to UKC registered American Pit Bull Terriers.

Breed-specific legislation
Areas that have passed breed specific legislation banning or restricting the ownership of Pit Bulls and "pit bull type" dogs most often also ban the Amstaff, as the Amstaff is without a doubt an offspring and sister breed of the APBT. Most often, dogs are judged solely on their looks. Current practice for Pet Rescue facilities dictates that these most maligned animals go to very stable homes with solid family values. A very deep application process is normally involved with adoption to insure that the AmStaff or typical breed dog goes where it will be properly trained and cared for in a permanent family environment.