Repeated defeats by Russia are generally acknowledged as a major motivation for Selim III’s restructuring of Ottoman government. Yet scholarship on the Russo-Ottoman Wars, and on the eighteenth-century relations between the two empires more generally, has too often remained focused on war and diplomacy from the standpoint of generals and diplomats. My paper takes up the story from a different, and almost entirely unstudied, direction: that of Russian prisoners of war. I first trace the changing status of prisoners in Ottoman-Russian, and Ottoman-Habsburg, treaties through the eighteenth century. While these changes are intriguing, and can be seen as one aspect of the “Europeanization” of Ottoman foreign relations, I argue that it is important not to mistake them for a literal representation of Ottoman or Romanov practice. Through an examination of period Ottoman chronicles, I show that on both sides, these realties were considerably more complex than the treaties claimed—and quite different from earlier practices, such as those during the 16th-17th century kleine krieg with the Habsburgs in Hungary. Focusing especially on the 1787-1792 War and its aftermath, my paper contends that there evolved a set of norms for prisoner treatment, seen in the practices and attitudes of both governing elites and ordinary soldiers and sailors. At the same time, the gap between these norms and the theoretical provisions of treaties could bring the misfortunes of ordinary captives to the center of international politics, as when relations between the Ottomans and Romanovs broke down in 1794 over Russia’s refusal to return some of its captives. But prisoners were not only important as passive subjects in elite political squabbles; Russian prisoners and renegades—categories which were frequently blurred—took an active part in Ottoman military reforms under Selim III. The activities of famous, and frequently self-promoting, European renegades, such as the Baron de Tott and Humbaraci Ahmed Bonneval, are well-known. But the often-anonymous Russian subjects who passed into Ottoman service also played important roles—for example forming the very first Ottoman unit using “the European discipline”—roles which my paper will attempt to trace. Finally, I will touch on broader questions this study raises—how did prisoners affect Ottoman perceptions of Russia? How significant was their involvement in reforms, and does this problematize the idea of Selim’s reforms as “Europeanizing,” given Russia’s own eighteenth-century debates over its place in Europe?