The thesis examines the thought of Thomas More and Gerrard Winstanley, emphasizing the concern of both theorists with the prevailing moral depravity of human nature attributable to the Fall of Man, and their proposals for the amendment of men's conduct by institutional means, especially by the establishment of a communist society. The thesis opens with a conceptual exploration of 'utopianism' and 'millenarianism' before discussing the particular forms of these concepts employed by More and Winstanley. The introductory section also includes an investigation of the context which constituted the background to the ideas of More and Winstanley. More's theology, his conception of human nature, and his view of contemporary civil society are examined in detail. It is argued that the conclusions More derived from this aspect of his thought formed his basic conception of the situation to which the institutional amendments outlined in Utopia were directed. These proposals, regarding communism, the state, family and community life, education, religion, and ethics, are discussed. It is argued that Utopia constitutes More's model of a society designed to facilitate the salvation of man. Winstanley's appreciation of man's nature, prevailing condition, and potential for spiritual regeneration, are outlined. The development of Winstanley's thought, and the impression his active involvement with the Diggers made upon him, is described. It is argued that Winstanley renounced millenarianism and ultimately assumed utopian social theory as a medium for the articulation of his proposals for the restoration of man to spiritual regeneracy on earth. The institutional aspects of this scheme, regarding communism, the state, patriarchalism, labour, and education, which he outlined in The Law of Freedom, are evaluated. The thesis concludes, with a brief comparative analysis before setting the ideas of More and Winstanley'in the context of the changing worldview, appreciation of man's potential and progress, and the emphasis upon aspiration, which evolved in the early modern period.