Psychiatry, Society, and Psycho-Politics in the German-speaking Countries, 1918-1939 Since the emergence of the discipline, the diagnostic concepts of psychiatry, more than those of any other medical field, have always been closely connected to normative debates about society at large. This link never was more apparent than in the two decades between the world wars. Amidst the political and social unrest, German-speaking psychiatrists attempted to directly interpret, diagnose, and treat society and politics from the perspective of their own clinical experiences. Leading members of the discipline redefined its boundaries and its area of authority to target larger populations beyond the mentally ill, and even the body politic as a whole. While this expansion of psychiatry’s area of expertise in the first third of the twentieth century has been noted by numerous scholars in the field, this is the first study that analyzes this process systematically and comprehensively. Using the concept of “psycho-politics” to describe the changing relation between psychiatrists and society in the period between the world wars, I maintain that these developments were neither monolithic nor disembodied processes. By situating different approaches in historical context, the thesis demonstrates how the social and political expansion of psychiatric expertise was motivated by very different reasons and took very different forms. I discuss three examples in detail: the overt pathologization of the 1918/19 revolution and its protagonists by right-wing German psychiatrists; the project of professional expansionism under the label of “applied psychiatry” in interwar Vienna; and the attempt to unite and implement different approaches to psychiatric prophylaxis in the German-speaking branches of the international movement for “mental hygiene.” Throughout these three interconnected case studies, I make a point for the importance of individual agency in the history of the psy-disciplines. I use the example of a number of eminent psychiatrists to show how the projects mentioned above were linked to their individual biographies and careers, and how their approaches were shaped by individual experiences of the political events in the first third of the twentieth century. Moreover, the study contributes to a broader understanding of the twentieth-century history of the psy-disciplines in at least three ways. First, I unearth the almost forgotten histories of some of the most important scholars and ideas that defined psychiatry in the first half of the twentieth century. Second, I explore the early history of some the concepts that still shape the field to the present day, namely mental health, deinstitutionalization, and psychiatric prophylaxis, as well as the history of psychiatric notions of social and political life that still circulate today. Third, I also examine psychiatry’s utopian promises, and show how the idea that the knowledge of the maladies of the human mind could pave the way to a better society could cut across contemporary political divides. The loftiest promises and the worst abuses of psychiatry were more closely connected than one might expect.