This paper examines the concept of “muhacir” (refugee or immigrant) in Turkey in the 1920s and 1930s. The term “muhacir” is a key migration category in late Ottoman and Turkish history, yet it remains poorly understood because of how often its meanings shifted and how widely it has been applied. The category of “muhacir” came into widespread Ottoman usage after the Crimean War of 1853–56. While it legally applied to all immigrants irrespective of their faith, Ottoman administrators typically used it only for Muslim refugees from the Russian Empire, perhaps staying close to the traditional meaning of the term in Islamic history, denoting a Muslim refugee escaping religious persecution to a Muslim country. By the 1880s, the term was occasionally used for non-Muslim immigrants, such as Jewish immigrants in Palestine. In 1913, the Ottoman government linked the category of “muhacir” to one’s manner of naturalization, with only those whose former nationality had been canceled entering the empire as “muhacir.” In early republican Turkey, “muhacir” remained the dominant term to describe incoming refugees and immigrants. Unlike the Ottoman administration, republican authorities introduced stricter admission policies for foreign Muslims. At different times, Ankara prioritized different elements of migrants’ identities: a religious identity (Muslim), an ethnic identity (Turkish or Turkish-adjacent), or national origin. A “muhacir” was no longer any refugee or immigrant but a certain kind deemed assimilable into, and beneficial for, Turkish society. On the legal plane, the term coexisted, and sometimes overlapped in usage, with mülteci (refugee) and mübadil (exchangee). Based on research in Cumhuriyet Arşivi (Republican Archive) and Turkish newspapers, this paper explores contested meanings of the category of “muhacir.” This study contributes to our understanding of (a) how the boundaries of the Turkish nation were constructed; (b) the legacy of Ottoman migration in the republican period; and (c) the relationship between the Turkish state and foreign post-Ottoman Muslims.