In 1852, the leadership of the Church of Jesus Christ of Latter-day Saints made the pivotal decision to publicize the doctrine and practice of plural marriage—something they had worked to keep out of the public eye for years. This decision came in response to federal and social pressures. They quickly moved to announce and defend plural marriage among Church members as well as broader society, including those in the federal government. Orson Pratt was chosen by Brigham Young to be the face and the voice of the Church concerning plural marriage, both in Salt Lake City among members and in Washington D.C., where he preached sermons and published a periodical on the subject. This thesis a) demonstrates why Orson Pratt was the ideal candidate for such an undertaking; b) assesses the motivation for and context of the public unveiling and defense of plural marriage; c) analyzes Pratt’s rhetoric of the first public treatise on the subject given to a Latter-day Saint congregation at a special conference on 29 August 1852; and d) compares the rhetoric and reasoning between Pratt’s sermon to the Saints and his persuasive periodical written to the nation from Washington D.C. titled The Seer. Pratt’s rhetoric is incisive and carefully tailored to his audience. Important nuances in argumentation arise as he publishes the Seer and strives to convince his fellow citizens that plural marriage is right before God, improves society, and that the Saints should be allowed to practice polygamy as an expression of religious freedom. Orson Pratt ultimately fails to make a difference in the national opinion of plural marriage, but is successful in establishing a foundation of principles and reason that would be employed by the Saints to defend the practice of plural marriage for decades.