This dissertation examines the singlemost explosive political event of the Polish interwar period: Joseph Pi1⁄2sudski's 1926 coup d'état and the period of "'Sanacja'", or "cleansing" that it inaugurated. I argue that the Sanacja's language of purification, health and rebirth resonated forcefully outside of the strictly political and military contexts in which the event is customarily considered. It is generally argued that Pi1⁄2sudski carried out the coup in the name of political stability, and that his goal was to reform a corrupt and incompetent public service. As a mandate, however, the Sanacja was singularly imprecise; invocations of morality, virtue and civic courage--over practical reform measures. The utopian vagueness of the Sanacja, the very malleability and mobility of its language, made it available to all, opponents and proponents alike, as a set of ideas with which to critique contemporary social, political, and moral ills, and as an idiom in which to articulate visions of what independent Poland should be. To supporters of Pi1⁄2sudski, the Sanacja, with its appeals to active and responsible citizenship, held the cure for the spiritual and intellectual malaise that afflicted post-partition Poland. For right-Catholic-nationalist opponents of the coup, the Sanacja, supported as it was by agents of secular reform, was itself evidence of moral rot. This radical polarization of interwar Polish society underlies the argument that Pi1⁄2sudski's coup should be understood as the dramatic clash of what contemporary writer Maria Daƒbrowska termed Poland's "moral nations". This dissertation is organized around some of the various ways in which different groups and individuals responded to, used and understood the Sanacja. It draws upon a wide variety of texts, including contemporary press coverage, the personal and professional papers of notable interwar figures (such as those of Zofia Moraczewska, Aniela Samotyhowa and Kazimiera I1⁄21⁄2akowiczówna), and organization records (such as those of the Women's Democratic Election Committee, the Women's Union for Citizenship Work, and the Society for the Moral Rebirth of the Nation). Other personages who figure in this study include: Tadeusz Boy Z¤elen ́ski, Zygmunt Wasilewski, Aleksander S ́wieƒtochowski, and Adolf Nowaczyn ́ski.