Americans of Joseph Smith’s day, steeped in the stories and prophecies of the King James Bible, certainly knew about plural marriage; but it was a curiosity relegated to the misty past of patriarchs Abraham and Jacob, who never gave reasons for their polygamy. It was long abandoned, Christians understood, by the time Jesus set forth the dominating law of the New Testament. But how did Joseph Smith understand it? Where did it fit in the restitution of all things (Acts 3:21) predicted in the New Testament? What part did it play in the global ideology declared by this modern prophet who produced new scripture, new revelation, and new theology? During Joseph Smith’s lifetime, polygamy was taught and practiced in intense secrecy, with the result that he never fully explained its doctrinal underpinnings or systematized its practice. As a result, reconstructing Joseph Smith’s theology of plurality is a task that has seldom been undertaken. Most theological examinations have either focused on its development during Brigham Young’s Utah period, with its need to resist increasing federal legislative and judicial pressures, or the efforts of twentieth-century and contemporary fundamentalists who continue to marry a plurality of wives. Volume 3 of this three-volume work builds on the carefully reconstructed history of the development of Mormon polygamy during Joseph Smith’s lifetime, then assembles the doctrinal principles from his recorded addresses, the diary entries of those closely associated with him, and his broader teachings on the related topics of obedience to God’s will, marriage and family relations, and the mechanics of eternal progression, salvation, and exaltation. The revelation he dictated in July 1843 that authorized the practice of eternal and plural marriage receives unprecedented examination and careful interpretation that illuminate this significant document and its underlying doctrines. Attempts to explain the history of Joseph Smith’s polygamy without comprehending the theological principles undergirding its practice will always be incomplete and skewed. This volume, which takes those principles and evidences with the utmost seriousness, has produced the most important explanation of why this ancient practice reemerged among the Latter-day Saints on the shores of the Mississippi in the early 1840s.