The chapter discusses the two major international military orders of the high Middle Ages, the Templars and the Hospitallers. It outlines their origins in the twelfth-century Crusader kingdom of Jerusalem, as well as the factors that contributed to their emergence, such as pilgrimage, the eleventh-century Church reform, knighthood and chivalry, the Crusades, and the role of the papacy. It then considers the comparative historiography of Templars and Hospitallers, including the scholarly debate on the Templars’ suppression and the Hospitallers’ survival. The chapter goes on to address the question of the military orders’ identity by examining the extent of the Templars’ charity and hospitality, the question of the Hospitallers’ militarization, and the genesis of the concept of an ‘order state’. It concludes with suggestions for future research.