What I will write a book elucidating how the Catholic Church affected the development of institutions of political constraint (parliaments and self-governing towns) in medieval and early modern Europe. This is a subject that has been neglected in recent social science work on European state-formation, despite the fact that historians consistently emphasize the crucial role played by the Church in this period. The book promises to shed light on the paradoxical fact that political institutions such as parliaments and urban self-government arose in back-of-beyond Western and Northern Europe, and not in the older and initially better endowed civilization centres in the Middle East and East Asia, where warfare – another factor that has been singled out in prior literature – was also pervasive. Why Social scientists have recently revisited the importance of religious institutions and teachings for, inter alia, modern democratization and economic growth. However, the attempt to bring religion back in has been almost completely ignored in a new and influential literature on European state-formation, which has flourished in recent decades. The premise of this book is that we cannot grasp the European development shorn of considerations about ecclesiastical-lay political interactions. Moreover, we are living in an age where religion and politics are again interacting in ways secularists had not foreseen a couple of generations ago, and the book will show how a study of medieval and early modern Europe can inform present-day debates about religion and politics. How The book combines quantitative and qualitative research. First, in a series of quantitative analyses, it probes whether the effects of the Church on institutions of constraints identified by narrative historical research can be corroborated using state-of-the-art approaches to identifying causal effects in a setting where random assignment is not possible. Second, in a series of historical process-tracing analyses, it traces the actual ecclesiastical actors who affected the lay development of institutions of constraints and identifies the ways they did so. Third, it carries out comparative historical contrasts between the Latin West and the Orthodox Christian areas of Europe as well as Muslim polities in the Middle East, all of which share the same inheritance from Antiquity.