The Aryan Brotherhood, or AB, is a predominantly Caucasian (White) gang that originated in California's San Quentin State Prison in 1967. The AB was first established to protect its members from the more numerous Black and Mexican gangs. They are said to have grown out of another prison gang, the Blue Bird Gang, that was active from the late 1950s to the 1960s. Chapters also allegedly exist in homeless shelters in several large American cities, including New York, and some law enforcement officials believe that the Freight Train Riders of America may be affiliated with the organization.

It is generally believed that prospective members were originally required to be of Irish descent, but that this requirement was later revoked. Today, although the membership is still mostly Caucasian and they continue to use symbols associated with Nazi Germany, the AB includes some non-White members, and they work actively with non-White gangs such as the Mexican Mafia (MM or EME).

AB symbols include the Nazi "SS" bolts and swastika, the number "666," the letters "AB," and the shamrock (as a symbol of their originally Irish membership).

AB members who are released from the prison system are expected to maintain their ties to their incarcerated kindred and even continue to provide active support by sending money or smuggling drugs into the prisons. Members, in and out of the prison system, have been connected to robberies, assaults, murders (including contract killings), and drug dealing (especially marijuana and methamphetamines).

The AB is believed to have connections to Aryan Nations, a neo-Nazi organization that follows a religious ideology known as Christian Identity. However, in some areas, AB's are said to be using the neo-pagan religion Odinism to disguise their gang activities.

Source: FBI file released under the Freedom of Information Act. Subject: Aryan Brotherhood. File Number: 183-7396

See also: Organized crime