The emergence of the category of enemy nation and the practice of ethnic cleansing (that is, the forcible relocation of an ethnically defined population away from a given territory) was one of the most momentous developments in the Soviet nationalities policy of the mid-1930s. My account of the origins of Soviet ethnic cleansing will attempt to address this paradox by showing how the same principles that informed Soviet nation-building in the 1920s, under certain conditions, could and did lead to ethnic cleansing and ethnic terror against a limited set of stigmatized nationalities, while leaving nation-building policies in place for the majority of nonstigmatized nationalities.