The principle of plural marriage was first received by Joseph Smith through revelation in early 1831 but was not committed to writing until July 12, 1843 in Doctrine & Covenants 132. It was then practiced by a small percentage of church members until 1890 when President Wilford Woodruff, 4th president of the LDS Church, received a revelation to discontinue its practice as recorded in Official Declaration 1.
Over the years LDS Church leaders have spoken out against polygamy. Regarding the polygamous group in Texas that calls itself the FLDS, Elder Quentin L. Cook of the Quorum of the Twelve Apostles said:
"Mormons have nothing whatsoever to do with this polygamous sect in Texas. The fact is that The Church of Jesus Christ of Latter-day Saints officially discontinued the practice of polygamy in 1890: 118 years ago. It's a significant part of our distant past, not of our present" ("Church Seeks to Address Public Confusion Over Texas Polygamy Group").Although it's easy to become confused by media headlines which often refer to polygamous groups as "Mormon fundamentalists," "Mormon families," or "Mormon Polygamous Clans", it's important to remember that today polygamy is in no way connected with the LDS Church. These titles are misleading and are a contradiction in terms. The term Mormon is a nickname applied exclusively to The Church of Jesus Christ of Latter-day Saints and its members. Since polygamy was denounced by the LDS Church over a century ago and members who embrace this practice today are excommunicated, the term "Mormon polygamist" is false.