Pontiffs from the Middle Ages to the present have portrayed Islam in widely differing terms. Indeed, before the twentieth century, popes rarely employ the terms “Islam” and “Muslim,” preferring terms such as “Saracens,” “Turks,” or “Mohammedans.” The ways they portrayed Islam and Muslims varied according to the perceived doctrinal and military threat posed to the Roman Church and according to the individual inclinations of different popes. But they also varied (sometimes in the writings of the same pope) according to a variety of specific interests: the popes’ engagement with Islam and Muslims is alternately military, political, diplomatic, theological, or pastoral. Hence very different assessments of Islam and Muslims emerge from a great diversity of papal sources: crusading encyclicals, canon law texts dealing with the legal status of Muslims living in Christian lands, letters to Muslim rulers, correspondence with Church officials in Muslim territories (bishops, friars, missionaries, or others). This brief chronological survey examines the varying and evolving portrayals of Islam and Muslims in papal documents, from the early Middle Ages through Vatican II and until the pontificate of Francis I.