The years of Japanese colonial rule, 1910–1945, saw the emergence of a powerful popular Korean nationalism. This sense of national identity both competed with and was shaped by other transnational identities: with the Japanese Empire, with East Asia, with the “civilized and enlightened” global order centered in the West, and with the international proletariat movement. These various forms of identities were part of a colonial cosmopolitanism that characterized the new urban middle class and the intellectuals of this period. The various trans-national identities often contested with each and contributed to the ideological divisions that emerged in the nationalist movement and had a major impact on the development of Korea after liberation in 1945. This article looks at the various ways Koreans in the colonial period identified with communities beyond Korea.