This study uses the analysis of communication practices and strategies to argue for a new understanding of papal power in the years 1050 to 1250. Historians frequently argue that the high medieval papacy increased the scope and effectiveness of its authority through the creation, maintenance, and use of centralized governmental institutions. According to this view, legates, councils, delegated justice, legal codification, and a remarkable production of letters all allowed the bishops of Rome to reach into the far corners of Christendom to shape in profound ways the spiritual, political, and economic trajectories of medieval Europeans. But how effective were those institutions? To what degree was the papacy able to implement policy at the local, national, and international levels? The following study attempts to answer this question by considering the specific communicative mechanisms and strategies that the papacy employed in a variety of policy realms. Four case studies analyze the papacy’s efforts to: 1) resolve the York-Canterbury primacy dispute at the turn of the twelfth century; 2) mobilize political support during the papal schism of 1159; 3) reform the Church in the wake of the Fourth Lateran Council of 1215; and 4) convene the Council of Rome to fight Emperor Frederick II in 1240. Each case reveals innovations in papal communication practices while simultaneously highlighting key limitations in the papacy’s ability to implement its will. The papacy, once a model of institutional centralization for medieval historians, suddenly appears much less centralized—and, in many cases, much less effective—of an institution than many scholars had led us to believe. This conclusion forces us to rethink what we know about one of the single most important institutions in European history.