Apostolic United Brethren

The Apostolic United Brethren (AUB) is a Mormon fundamentalist group that practices polygamy and is no longer associated in any way with the Church of Jesus Christ of Latter Day Saints. The AUB has had a temple in Mexico since the 1990s, an endowment house in Utah since the early 1980s, and several other locations of worship to accommodate their members in the US states of Wyoming, Arizona, and Montana.

The title "Apostolic United Brethren" is not generally used by members, who prefer to call it "The Work," "The Priesthood," or "The Group." Those outside the faith sometimes refer to it as the "Allred Group" because two of its presidents shared that surname. Most members of the AUB do not refer to their organization as a "church" and, unlike nearly all other Mormon fundamentalist groups, regard the Church of Jesus Christ of Latter-day Saints (LDS Church) as a legitimate, if wayward and diminished, divine institution.

Religious scholar J. Gordon Melton characterised the group as "the more liberal branch of the Fundamentalist movement", as the group allows sexual relations apart from the strict purpose of procreation.

The group came into the Hollywood spotlight with the debut of the hit reality TV series Sister Wives in 2010. The show chronicles the lives of the Kody, Meri, Janelle, Christine, and Robyn Brown, who were AUB members for the first few years of the series. (As of 2025, the show is in its 19th season and most of the Brown family are no longer AUB members).

The AUB furnished a detailed description of their beliefs and practices in August 2009 to the Utah Attorney General's "Polygamy Primer," which was later revised in 2011. This booklet is used to educate the law enforcement and social relief agencies involved with similar groups.

The AUB is unrelated to other similarly named groups such as Churches of the Brethren and Apostolic Pentecostals.