In a seventeenth-century English landscape populated with towering political and philosophical figures - Hobbes, Harrington, Cromwell, Milton, Locke - William Penn (1644-1718) remains a man apart, a figure whom many know a little, but few know well. In Liberty, Conscience, and Toleration,Andrew Murphy shows that, despite widespread scholarly neglected, William Penn was a sophisticated political thinker who contributed in decisive ways to the theory and practice of religious liberty in the early modern Atlantic world. The book elucidates the various political conflicts in which Pennparticipated, and the ways in which they facilitated the development of his political ideas over a forty-old-year political career. Murphy's picture of Penn's political thinking unfolds over the course of five engaging chapters, which focus on the main political episodes that occasioned his sustained attention as a political thinker and actor: the controversy over the Second Conventicle Act (1668-1670); the Popish Plot andExclusion Crisis (1678-1681); the founding and settlement of Pennsylvania (1681-1684); and the contentious reign of James II (1685-1688). The book contextualizes the development of Penn's thought in England and America through analysis of his published writings in the midst of the religio-politicalconflicts of Restoration and Revolutionary England, illuminating the mutual interconnections between Penn's political thought and his colonizing venture in America. William Penn played a crucial role in the contentious emergence of religious liberty and remains a singular figure in the history of liberty of conscience. Penn's remarkable political theorizing provides a window into the increasingly vocal, organized, and philosophically sophisticated tolerationistmovement that gained strength over the second half of the seventeenth century. Not only did Penn attempt to articulate principles of religious liberty as a Quaker in England, but he actually governed an American polity and experienced firsthand the complex relationship between political theory andpolitical practice. Murphy's analysis highlights Penn's ongoing significance to the broader study of Anglo-American political theory and practice and the history of political thought. The examination of Penn's political thought ultimately points scholars toward a new way of understanding the historyof political thought and the enterprise of political theory itself: what it is, where and how it is produced, and how it relates to political practice.