Europeans intervened in the Ottoman Empire throughout the nineteenth century to increase their influence by “protecting minorities” they defined as at-risk. They offered non-Muslims and “heretical” Muslims special privileges and foreign education as protégés of the powerful European Great Powers. Watershed events in late Ottoman history read like a litany of European interventions in Ottoman affairs “on behalf of” the people deemed to be minorities: pressure to reform [leading in part to the Tanzimat, 1839-1876], the Crimean War [1854-56], the Lebanon crisis [1860], and the Balkan wars [1912-13]. In each of these interventions, “minority” status was based on religion. By the end of World War I, the victorious powers had become convinced that linguistic—or “national”—minorities had created the conflagration that had engulfed the world. To prevent the recurrence of such a catastrophe, the US president called for self-determination of peoples, and the Great Powers imposed sovereignty-limiting “Minorities Treaties” on newly-created states. European defined minorities by language, and the new Minorities Treaties System [1919-1923] provided certain rights for those living in a state defined by a different language-group. They were to be provided access to education in their own language, permitted to their language during official business, and shown respect for their distinctive cultures. The last years of the Ottoman Empire and the first decades of its successor state struggled to make sense of the new definitions of majority and minority. As Turkish nationalist forces fought off a Greek invasion, Europeans sought to define the contending parties according to their new paradigm. League of Nations officials contended that “Greeks” and “Turks” were different races, but defined these “racial” distinctions by religion. While language was largely irrelevant as a distinguishing category during the end of the Ottoman Empire, religion was unacceptable according to the new European notions of affiliation. With the defeat of the Ottoman Empire, Europeans maintained their insistence on protecting the newly-defined “minorities” in its former territories. Their interventions, reformulated to conform to the new emphasis reflected in the “Minorities Treaties,” led not only to escalating conflict among the residents of disputed Alexandretta and Mosul, but also to a catastrophic “exchange of populations.” Using sources from the League of Nations, the local press, and French, British, and American archives, this paper seeks to reinterpret late-Ottoman “minorities” policies by comparing them to the new assumptions introduced into the region by the European Minorities Treaty regime.