This study seeks to answer a fundamental question facing missiologists and historians of Mormonism: given their sustained preoccupation with converting others to Mormonism and their thriving tradition of missionary work, how do Mormons conceive of their mission? By focusing on the theoretical frame in which Mormon missionaries imagined the non-Mormon world, prepared for missionary engagement, and derived their expectations for their mission work, this study aims to illuminate the development of Mormon missionary activities and explain the processes by which Mormons fashioned for themselves a missional character. Beginning with Joseph Smith and the emergence of his missional thought and ending with the institutional shifts of the Mormon Church toward mission programs, this thesis attempts to map the general arc of Mormon mission theory as it developed within the context of early American religious history.