The growth and distribution of the Latter Day Saint Church between 1840 and 1860 is an aspect of Welsh history and geography which has received little attention. Studies of Mormonism in Wales have tended to focus on the general history of the church, or on spirituality and eschatology, with only little reference to the society in which it developed. This study examines Mormonism in Wales as part of a radical Christian movement which arose among the working class of Britain. This movement developed alongside the radical movement in Britain, and is typified by Christian Chartism. Radical Christianity can be characterized as anti-clerical, anti-creedal, Arminian, and, sometimes chiliastic. It was marked by the view that Christianity and communism were compatible, and that Christianity, rather than being a passive means of coping with social conditions, could provide a powerful ideology with which to bolster secular attempts at reform. As a means of establishing the radical nature of Mormonism and the basis of its appeal to a portion of the Welsh proletariat, Mormonism is examined in its American context. The social climate in which its doctrines originated is discussed, with reference to the characteristics of radical Christianity noted above. These include: doctrines concerning the priesthood; salvation; the United Order, which provided the basis of Mormon communism; and the progression of men to godhood. Finally, Mormonism is examined in relation to Nonconformity, to Welsh society in general, and to a growing radical, national identity among the Welsh. The distribution of Mormon congregations is discussed in relation to denominationalism throughout Wales, with the purpose of explaining a primarily urban-industrial distribution, concentrated in the valleys of Monmouthshire and eastern Glamorgan. The thesis concludes with a review of methods of diffusion, followed by a discussion of reasons for Mormonism's decline in the 1850s and 1860s.