Polygamy in the Church of Jesus Christ of Latter Day Saints, called plural marriage, is generally believed to have originated with the founder of Mormonism, Joseph Smith. According to several of his associates, Smith taught that polygamy was a divine commandment and practiced it personally, by some accounts marrying between 30 and 40 wives, some of whom had existing marriages to other men. Evidence for Smith's polygamy is provided by the church's "sealing" records, affidavits, letters, journals, and diaries. Until his death, Smith and the leading church quorums publicly denied that he preached or practiced polygamy. Smith's son Joseph Smith III, his widow Emma Smith, and the Reorganized Church of Jesus Christ of Latter Day Saints (RLDS Church, now called Community of Christ) challenged the evidence and taught that Joseph Smith had opposed polygamy. They instead stated that Brigham Young, the head of the Church of Jesus Christ of Latter-day Saints (LDS Church), introduced plural marriage after Smith's death. In 1852, leaders of the Utah-based LDS Church publicly announced the doctrine of polygamy.

1830s: origins When polygamy was introduced into the Latter Day Saint movement is uncertain."It is difficult to determine exactly when Joseph Smith first felt compelled to practice polygamy."

Possible revelation in 1831

Some scholars believe that Smith transcribed a revelation recommending polygamy on July 17, 1831. This revelation is described in a letter to Brigham Young written in 1861 by an early Mormon convert, William W. Phelps, thirty years after the revelation was said to be given. This was during a period when LDS Church leaders were justifying the practice and origins of plural marriage, particularly to Mormon splinter groups who did not agree with the practice.

The key portion of the revelation proclaims:

This wording is comparable with the portion of the 1830 edition of the Book of Mormon, which corresponds to today's 2 Nephi 30:5–6, which states that when Lamanites and Nephites receive the gospel they will become a "white and a delightsome people." Unlike the 1831 revelation, the 1830 version of the Book of Mormon does not specify that the Native Americans would become "white and delightsome" through plural marriage. A note from Phelps in the same document explains how the conversion of the Native Americans coincided with Smith's plan for a new system of marriage:

A reference was made to this revelation five months after its alleged date in a letter by Mormon apostate Ezra Booth to the Ohio Star on December 8, 1831, in which he refers to the "revelation [that the Mormon Elders] form a matrimonial alliance with the Natives", but the letter makes no reference to polygamy.Ezra Booth, letter dated December 6, 1831, Ohio Star (Ravenna, OH), December 8, 1831. Text at Saints Without Halos, archived from the original on June 7th, 2011. Reprinted in . This letter is significant in that it confirms that a revelation about marrying Natives occurred, but it is also problematic for multiple reasons. One is the context for the revelation. Mormon missionaries had been denied access to the Indian Territory as they lacked authorization from the US Indian Agents. They sought access multiple times and were never granted permission. To circumvent this, they were to get a license from the government to trade goods with the Indians and while trading "disseminate the principles of Mormonism among them." In addition to the trading license, marrying the Natives would be an additional means of circumventing the US Indian Agents.

The LDS Church never published Phelps's note or letter, nor has it been canonized as part of Mormon scripture. In 1943, historian Fawn Brodie stated that Joseph Fielding Smith, then LDS Church historian, told her that a revelation foreshadowing polygamy had been written in 1831 but never published, and that although its existence in the church library is acknowledged, "in conformity with the church policy", Brodie would not be permitted to examine it. Three authors assert that a second record of the revelation exists, believed to be in the LDS Church's historical department,

Though the 1831 revelation is cited by Mormon historians,"[T]he Prophet understood the principle of plural marriage as early as 1831. ... [a]ccording to Elder Phelps, the revelation then indicated that in due time the brethren would be required to take plural wives." () non-Mormon historians, and critics, there are dissenting opinions, and no consensus has been reached. Historians Leonard Arrington and Davis Bitton refer to the Phelps's document as "a copy of a purported revelation," and conclude that "obviously possibilities [for polygamy] were being considered in the early 1830s." Richard Van Wagoner questioned the thirty-year gap between the revelation and Phelps's later recollection: "[T]he Phelps letter has been widely touted as the earliest source documenting the advocacy of Mormon polygamy, [but] it is not without its problems. For example, Phelps himself, in a 16 September 1835 letter to his wife, Sally, demonstrated no knowledge of church-sanctioned polygamy: 'I have no right to any other woman in this world nor in the world to come according to the law of the celestial kingdom. David J. Whittaker contends that in 1861 it is "possible that Phelps added his own understanding thirty years later, Ezra Booth confirms early talk about marrying Indians, but the reasons for doing so probably did not include polygamy or even changing skin color, but rather facilitating entrance into the reservation for missionary work."

Early teachings and practice

After Smith's death, many early converts, including apostles Brigham Young,Journal History, August 26, 1857; cited by Hyrum Leslie Andrus, Doctrines of the Kingdom (Salt Lake City: Desert Book., 1999), 489n436 () Orson Pratt, and Lyman E. Johnson, said that Smith was teaching plural marriage as early as 1831 or 1832. Mary Elizabeth Rollins Lightner, Smith's ninth wife, , and . said that Smith had a private conversation with her in 1831 when she was twelve., link.Mary Elizabeth Rollins Lightner to Emmeline B. Wells, Summer 1905, LDS Church Archives.

Pratt reported that Smith told some early members in 1831 and 1832 that plural marriage was a true principle, but that the time to practice it had not yet come.Orson Pratt, "Celestial Marriage", Journal of Discourses, reported by David W. Evans (October 7, 1869), vol. 13 (London: Latter-day Saint's Book Depot, 1871), 192–293. Johnson also reported having heard the doctrine from Smith in 1831.Lyman Johnson as recounted by Orson Pratt, "Report of Elders Orson Pratt and Joseph F. Smith", Millennial Star, vol. 40, no. 50 (December 16, 1878): 788. Mosiah Hancock reported that his father Levi W. Hancock was taught about plural marriage in the spring of 1832.Todd M. Compton, In Sacred Loneliness: The Plural Wives of Joseph Smith (Salt Lake City: Signature Books, 1997) p. 644; citing Mosiah Hancock Autobiography, 61–62.

William Clayton, Smith's scribe, recorded polygamous marriages in 1843, including unions between Smith and Eliza Partridge, Emily Partridge, Sarah Ann Whitney, Helen Kimball, and Flora Woodworth.

Jacob Cochran Latter Day Saint historical sources indicate that as early as 1832, Mormon missionaries were converting followers of religious leader Jacob Cochran, who went into hiding in 1830 to escape imprisonment for practicing polygamy. Mormons held two conferences at Saco, Maine, the center of Cochranism, on June 13, 1834,Evening and Morning Star 2 [August 1834]: 181. and August 21, 1835. At the latter conference, at least seven of the twelve newly ordained Mormon apostles were in attendance,Messenger and Advocate 2 [October 1835]: 204–207: "On August 21, 1835, nine of the Twelve met in conference at Saco, Maine"History of the Reorganized Church of Jesus Christ of Latter Day Saints 1:583.History of the Church 2:252. including Brigham Young. Young became acquainted with Cochran's followers as he made several missionary journeys through Cochranite territory from Boston to Saco,Times and Seasons 6 [November 1, 1845]. and later married Augusta Adams Cobb, a former Cochranite, as one of his plural wives.Stewart, J. J. (1961) Brigham Young and His Wives, p. 85.Carter, K. B. (1973) Our Pioneer Heritage 6, 187–189. Others who spent time among the Cochranites were Orson Hyde and Smith's younger brother, Samuel.Journal of Orson Hyde and Missionary Journal of Samuel Harrison Smith 1832, LDS Church Historical Department, Salt Lake City.

Among Cochran's marital innovations was "spiritual wifery". Ridlon wrote in 1895, "tradition assumes that [Cochran] received frequent consignments of spiritual consorts, and that such were invariably the most robust and attractive women in the community."Ridlon, G. T. "Cochran Delusion/Mormon Invasion", Saco Valley Settlements and Families: Historical, Biographical, Genealogical, Traditional, and Legendary (Rutland, Vermont: Charles E. Tuttle, 1895) pp. 269 ff. Some new Cochranites remained polygamists, and moved from the east coast to the Mormon community of Kirtland, Ohio.Miller, T. (2005) "Social roots of the Mormon United Order" (Center for Studies on New Religions, University of Kansas).

1840s: development and fallout 1843 revelation

On July 12, 1843, Joseph Smith is said to have received a revelation that is much more widely accepted by historians. The revelation was supposedly dictated by Smith to his scribe William Clayton, and was shared with Smith's wife Emma later that day. Clayton wrote in his journal:

In the text of the revelation, it also states that the first wife's consent should be sought before a man marries another wife, but also declares that Christ will "destroy" the first wife if she does not consent to the plural marriage, and that if consent is denied the husband is exempt from asking his wife's consent in the future."[I]f she receive not this law ... she then becomes the transgressor; and he is exempt[.]" The final portion of D&C 132:65 has been interpreted as meaning that the husband is exempt from asking for his wife's consent in the future.

The revelation states that plural wives "are given unto him to multiply and replenish the earth, according to my commandment, and to fulfill the promise which was given by my Father before the foundation of the world, and for their exaltation in the eternal worlds, that they may bear the souls of men."

The revelation was not made public to the LDS Church as a whole until Brigham Young publicly acknowledged it in 1852. Young stated that the original had been burned by Smith's widow Emma Smith, though Emma denied that the document ever existed and said of the story told by Young: "It is false in all its parts, made out of whole cloth, without any foundation in truth."Church History, volume 3, p. 352. Published affidavits by eyewitnesses accusing church leaders of following the teaching and engaging in polygamy had resulted in Smith's murder by a mob in 1844. The revelation was codified in the LDS Church's canon as its Doctrine and Covenants section 132 in the 1870s. The 1843 revelation was rejected by the RLDS Church as not originating with Smith.Tandy, J. "Differences between the RLDS and LDS Doctrine and Covenants on the subject of Marriage". Emma Smith said that the first she knew of the 1843 revelation was when she read of it in Orson Pratt's newspaper The Seer in 1853.Saints' Herald 65:1044–1045.

Before Smith's death Records show that Smith publicly preached and wrote against the doctrine of plural marriage;Times and Seasons, vol. 5, p. 423, 474, 490–491. however, it is also clear that Smith performed dozens of plural marriages. Allegedly, "several were still pubescent girls, such as fourteen-year-old Helen Mar Kimball". Kimball, Smith's 28th wife, wrote of her experience in 1843–44,