Fundamentalist Mormon Groups and Modern Polygamy

Explore the history, beliefs, and societal impact of fundamentalist Mormon communities that continue to practice plural marriage outside the mainstream LDS Church.

By Garret Merkley · Explainer · Jun 3, 2026

Branched from Polygamy and Federal Authority: How the Church's Practices Deepened Conflict with the U.S. Government

Quick take

Fundamentalist Mormon groups are distinct from the mainstream Church of Jesus Christ of Latter-day Saints (LDS Church).
These groups practice polygamy, or plural marriage, believing it to be a divine commandment essential for exaltation.
They emerged after the LDS Church officially ended polygamy in the late 19th and early 20th centuries.
Their practices often lead to legal and social challenges, contrasting religious freedom with anti-bigamy laws.

Fundamentalist Mormon groups are independent religious communities that adhere to early doctrines and practices of Mormonism, most notably the practice of plural marriage, or polygamy. They are entirely separate from The Church of Jesus Christ of Latter-day Saints (LDS Church), which officially discontinued the practice of polygamy over a century ago.

How These Groups Formed and Operate

The origins of fundamentalist Mormonism trace back to the late 19th and early 20th centuries, following the LDS Church’s official abandonment of polygamy. In 1890, LDS Church President Wilford Woodruff issued the Manifesto, a statement that effectively ended the official practice of plural marriage in response to intense federal pressure and legislation. A second Manifesto in 1904 solidified this position, leading to the excommunication of members who continued to enter into plural marriages.

Those who believed polygamy was a non-negotiable, eternal commandment—essential for achieving the highest degree of salvation and exaltation in the afterlife—separated from the mainstream church. These dissenting members formed new communities, often in isolated areas, to continue practicing what they saw as the original, divinely mandated form of marriage. Key groups that emerged include the Fundamentalist Church of Jesus Christ of Latter-Day Saints (FLDS) and the Apostolic United Brethren (AUB), among others.

Within these groups, plural marriage is typically patriarchal, with one man married to multiple women. The structure of these communities can vary but often emphasizes strict adherence to their interpretation of religious law, a strong sense of community identity, and a degree of insularity from mainstream society. Children are raised within these specific religious frameworks, and marriage arrangements are often made within the community, sometimes involving underage individuals, which has led to legal controversies.

Why These Practices Persist Today

The persistence of fundamentalist Mormon groups practicing polygamy highlights a complex intersection of religious freedom, cultural tradition, and legal authority. For adherents, plural marriage is not merely a social custom but a sacred covenant believed to be commanded by God, necessary for spiritual progression and the ability to bear spirit children in the afterlife. This deeply held theological conviction provides a powerful motivation to maintain the practice despite external pressures and legal prohibitions.

Their continued existence also raises important questions about individual rights, particularly concerning women and children within these often closed communities. Cases involving underage marriages, child welfare, and alleged abuses have brought these groups into conflict with state and federal laws, prompting ongoing legal battles and public scrutiny. These situations underscore the tension between the constitutional protection of religious practice and the state's responsibility to protect its citizens from harm, especially when practices conflict with laws against bigamy, child abuse, or human trafficking.

Are fundamentalist Mormon groups part of the mainstream LDS Church?

No, fundamentalist Mormon groups are entirely separate from The Church of Jesus Christ of Latter-day Saints (LDS Church). They split from the mainstream church over the issue of polygamy and have distinct leadership, doctrines, and practices.

Is polygamy legal in the United States?

No, bigamy (the act of marrying someone while still legally married to another person) is illegal in all U.S. states. While some states have decriminalized certain aspects of plural cohabitation, the act of legally marrying multiple spouses remains prohibited.

How many people belong to these groups?

Exact numbers are difficult to ascertain due to the private and often insular nature of these communities. Estimates suggest tens of thousands of individuals live in fundamentalist Mormon communities across the Western United States and parts of Canada, though only a fraction of these may be actively practicing polygamy.

What are some common misconceptions about fundamentalist Mormonism?

A common misconception is that all Mormons practice or condone polygamy. This is incorrect; the vast majority of members of The Church of Jesus Christ of Latter-day Saints do not practice polygamy and have not for over a century. Another misconception is that all fundamentalist groups are alike; they vary significantly in their doctrines, leadership, and practices.

Sources

The Church of Jesus Christ of Latter-day Saints: Official Declarations 1 & 2 (Manifestos)
Utah Code Ann. § 76-7-101 (Bigamy statute)