The short answer is no. Mainstream Mormons do not practice polygamy. They used to over a century ago but have now stopped the practice entirely and those engaging in it are excommunicated. However, there are off shoots from the church that do still practice polygamy, and by association only, many people wrongfully assume all Mormons do.
The official Mormon website has this piece of information
President Gordon B. Hinckley, prior president of The Church of Jesus Christ of Latter-day Saints made the following statement in 1998 about the Church’s position on plural marriage:
“This Church has nothing whatever to do with those practicing polygamy. They are not members of this Church.... If any of our members are found to be practicing plural marriage, they are excommunicated, the most serious penalty the Church can impose. Not only are those so involved in direct violation of the civil law, they are in violation of the law of this Church.”
At various times, the Lord has commanded His people to practice plural marriage. For example, He gave this command to Abraham, Isaac, Jacob, Moses, David, and Solomon (Doctrine and Covenants 132:1). At other times the Lord has given other instructions. In the Book of Mormon, the Lord told the prophet Jacob “for there shall not any man among you have save it be one wife: and concubines he shall have none... for if I will, saith the Lord of Hosts, raise up seed unto me, I will command my people; otherwise they shall hearken unto these things (Jacob 2:27-30).
In this dispensation, the Lord commanded some of the early Saints to practice plural marriage. The Prophet Joseph Smith and those closest to him, including Brigham Young and Heber C. Kimball, were challenged by this command, but they obeyed it. Church leaders regulated the practice. Those entering into it had to be authorized to do so, and the marriages had to be performed through the sealing power of the priesthood. In 1890, President Wilford Woodruff received a revelation that the leaders of the Church should cease teaching the practice of plural marriage (Official Declaration 1).
The Lord’s law of marriage is monogamy unless he commands otherwise to help establish the House of Israel (see Encyclopedia of Mormonism Vol. 3, pp. 1091-1095).
And other commentors have answered
Nope. That ended over a hundred years ago.
No we do not. God has, at some points in time, commanded certain man to practice polygamy (i.e. Abraham, Jacob, Moses, David, and Solomon) but monogamy is always the norm and polygamy the exception even during these times. It is true that certain early Saints were called to practice plural marriage, however this was always closely monitored and had to be authorized through church leaders. Through President Wilford Woodruff in the year 1890, God commanded this practice to end and is no longer practiced by The Church of Jesus Christ of Latter-day Saints.
No, Mormons do not practice polygamy and discontinued the practice over a century ago. Yet, whenever I discuss my faith, often the first question asked is, "how many wives do you have?" It is important to know that the religious groups that currently practice polygamy, as often seen on the news, have no affiliation with the Church of Jesus Christ of Latter-Day Saints. Even though some of these groups may claim otherwise.
No. I am aware that there is a religious sect that does practice polygamy, however, our doctrine is definately about a one man and one woman relationship within marriage.
No, we don't. People typically mix up Mormons with their reformed break offs. Several of those groups practice polygamy, even though historically the commandment from the Lord to have plural marriages has been repealed.
No. Mormons do NOT practice polygamy. There are many people outside the Church that say otherwise, but that doesn't change the truth of the matter. There is nobody living on this earth right now who can truly claim to be a member of The Church of Jesus Christ of Latter-day Saints who practices polygamy. It is against the law, both of the land and of the Church. We do not approve of such things. There are some groups of people who do practice this and also claim to be Mormons, but I assure you that they are not in any way affiliated with this Church.
Today, Mormons are commonly associated with polygamy, even though the practice was discontinued in the Mormon Church in 1890 - over 120 years ago! Today there are still some who claim to be Mormon and who practice polygamy, but it should be recognized that they are not part of our Church - anyone belonging to The Church of Jesus Christ of Latter Day Saints today who practices polygamy is excommunicated and their names are removed from our rosters. In modern revelation, we learn that we are never supposed to practice this unless specifically told to by the Lord (through the prophet) as was the case with Solomon and David in the Old Testament. Know that we do not want to practice polygamy. I don't know any Mormons who do. We know that if we were asked to, the Lord would help us to understand why, as He will with any commandment. However, until that day (which we do not expect to ever come), we will neither practice it nor look forward to doing so.
Absolutely not!! This is one of the many myths about Mormon's that hollywood and the media continue to propogate. It is true that the early memebrs of the church did practice polygamy, but the church oficcialy denounced the practice 150 years ago!! If any church member today practices polygamy they are excommunicated. There are people who leave the LDS church and start their own religion base loosely on LDS beliefs. Some of them practice polygamy. They are NOT memebrs of the LDS (Mormon) chruch, nor do they have any affiliation with the LDS church.