This dissertation examines the production and circulation of ethnographic knowledge in sixteenth- and early seventeenth-century Venice. It argues that ethnographic writing served as the basis for defining religious and cultural difference in new ways. In order to better understand the development and significance of Venetian ethnographic writing, my research draws on a range of archival sources, including court records, diplomatic correspondence, library inventories, and private journals. From these sources, it is clear that an interest in customs, rituals, and ways of life not only became central in how Venetians sought to apprehend other peoples, it also had a very real impact at the level of policy, shaping how the Venetian state governed minority populations under its jurisdiction. While scholars have long treated early modern voyages of conquest and discovery as fundamental in the development of European ethnography, the evidence indicates a more complicated set of origins for early modern ethnographic thought. In Venice, these lay in the city’s commercial connections in the eastern Mediterranean, the development of diplomatic practice, and the daily reality of co-existence in a religiously and ethnically diverse city.