1835 -- In the 1835 version of the D&C, Section 101:4 , it declares, "Inasmuch as this church of Christ has been reproached with the crime of fornication, and polygamy: we declare that we believe, that one man should have one wife; and one woman, but one husband."
1838 -- Oliver Cowdery is excommunicated, at least in part, for accusing Joseph Smith of adultery with Fanny Alger.
1842 -- Church-owned Times and Seasons denies the practice of polygamy, declaring: "We declare that we believe, that one man should have one wife; and one woman, but one husband, except in case of death, when either is at liberty to marry again."
1844 -- In the History of the Church Vol. 6, Joseph Smith denies practicing polygamy. "What a thing it is for a man to be accused of committing adultery, and having seven wives, when I can only find one."
June 7, 1844 -- William Law, 2nd counselor in the 1st presidency, leaves the church over polygamy and Joseph's denial of it.
Soon thereafter, he publishes the 1st and only edition of the Nauvoo Expositor, which claims 1st-hand testimony from several sources that Joseph was practicing polygamy, counter to his public denials.
1852 - 1890 -- The U.S. Federal Government heavily pressures LDS Church to cease polygamy
1866 -- Brigham Young declares that, " The only men who become Gods, even the Sons of God, are those who enter into polygamy. Others attain unto a glory and may even be permitted to come into the presence of the Father and the Son; but they cannot reign as kings in glory, because they had blessing offered unto them, and they refused to accept them."
1904 -- LDS Church releases a "Second Manifesto", after charges were confirmed that polygamous marriages continued despite the 1890 revelation/announcement. This article reads:
"During the Senate investigation in 1904 concerning the seating of Senator-elect Reed Smoot, a monogamist but a member of the Quorum of the Twelve Apostles, Mormon Church President Joseph F. Smith presented what historians have called the "Second Manifesto" on 7 April 1904. It included provisions for the church to take action against those who continued to perform plural marriages and marry plural wives. Matthias Cowley and John W. Taylor, both apostles, continued to be involved in performing or advocating new plural marriages after 1904, and, as a result, Cowley was disfellowshipped and Taylor excommunicated from the church. In 1909 a committee of apostles met to investigate post-Manifesto polygamy, and by 1910 the church had a new policy. Those involved in plural marriages after 1904 were excommunicated; and those married between 1890 and 1904 were not to have church callings where other members would have to sustain them. Although the Mormon Church officially prohibited new plural marriages after 1904, many plural husbands and wives continued to cohabit until their deaths in the 1940s and 1950s."
1998 -- During an interview with Larry King on CNN, when asked about polygamy, President Hinckley stated:
"I condemn it, yes, as a practice, because I think it is not doctrinal. It is not legal. And this church takes the position that we will abide by the law. We believe in being subject to kings, presidents, rulers, magistrates in honoring, obeying, and sustaining the law."
