This research explores the project of ‘Dekady’ – ten-day festivals of art and music from different, mostly non-Russian Soviet republics, held in the Bolshoi Theater in Moscow in 1936-1953. It was the flagman project of Soviet cultural policy and its analysis is key for understanding the dynamics of cultural and national policies of the SU. The principal aim of ‘Dekady’ consisted of the creation of opera tradition in national republics with its subsequent ‘sovietization’. In January 1934 Stalin’s slogan “national in form and socialist in content” appeared for the first time in relation to music. This formula pinpointed the cultural and national policies of the Soviet state. In the 1930s the national policy of the Stalinist government implied the slow repudiation of ‘korenization’ program, which consisted in instrumentalization of nationalism in non-Russian republics. However, ‘korenization’ paradoxically continued to influence cultural policy much longer. The problem of the research is the intricate relation of Stalinist cultural and the national policies, which did not completely agree with each other. If national policy aimed at fostering ethno-cultural diversity, Stalin’s cultural policy strove to homogenize the socio-cultural space of the Soviet Union by making it ‘socialist in content’.