Do proleća 1917. godine, na teritoriji (bivšeg) Ruskog carstva našlo se nekoliko desetina hiljada ratnih zarobljenika Južnih Slovena, od kojih su se mnogi direktno uključili u revolucionarna događanja započeta padom monarhije u februaru. Nakon Oktobarske revolucije, hiljade Bugara, Hrvata, Slovenaca i Srba borile su se na strani boljševika. Od 1918. godine, imali su svoju Južnoslovensku komunističku grupu pri Boljševičkoj partiji, kao i novine Svetska revolucija. Grupa se, međutim, brzo sukobila po pitanju ustrojstva posleratnog projekta. Jedni su se zalagali za stvaranje Jugoslavije kao države Južnih Slovena, dok su drugi smatrali da buduća socijalistička država treba biti Balkanska federacija, stari projekat balkanske socijaldemokratije. Ovo neslaganje dovelo je u konačnici do odvajanja Bugara iz Južnoslovenske komunističke grupe. Iako pitanje buduće radničke federacije na Balkanu nije razrešeno čak ni formiranjem Komunističke internacionale, ova zaboravljena rana debata između tada vodećih južnoslovenskih komunista bila je uvod u kasnije marksističke rasprave o nacionalnom pitanju u Bugarskoj i Kraljevini SHS. Analiza ovih projekata otvara pitanja o prijemu boljševičkih ideja među Južnim Slovenima, kontinuitetu i diskontinuitetu marksističke misli među balkanskim socijalistima pre i posle 1917. godine, kao i o razvoju koncepta lenjinističkog prava na samoopredeljenje u kontekstu političke situacije na Balkanu u posleratnom periodu., By the spring of 1917, tens of thousands of South Slavic prisoners of war had found themselves on the territory of the (former) Russian Empire, and many of them took an active part in the revolutionary events which had begun with the collapse of the monarchy in February. After the October Revolution, thousands of Bulgarians, Croats, Slovenes, and Serbs fought on the side of the Bolsheviks. Beginning from 1918, they had their own South Slavic Communist Group of the Bolshevik Party, as well as a newspaper called Svetska revolucija (The World Revolution). However, the Group soon became divided over the question of building a future postwar order. Some communists supported the creation of Yugoslavia as a country of South Slavs, while others thought that the future socialist state must be a Balkan Federation, an old project of Balkan social democracy. The pro-Yugoslav current was composed primarily of people who were radicalized by the world war and the revolution and who fought together in the South Slavic units of the Russian Imperial Army before 1917. The supporters of a Balkan federation were those who were active in the labor movement before 1914. The Bulgarian communists, influenced by the theoretical tradition of “narrow socialism” developed by Dimitar Blagoev, were the standard bearers of the idea of Balkan federalism, while most Serbs, Croats, and Slovenes eventually opted for Yugoslavia, also as a federal state. This disagreement eventually led to the separation of Bulgarians from the South Slavic Communist Group. Even though the question of the future workers' federation in the Balkans was not ultimately resolved even after the creation of the Communist International, this forgotten early debate between the leading South Slavic communists foreshadowed the later Marxist discussions on the national question in Bulgaria and Yugoslavia. The analysis of these projects raises new questions regarding the reception of Bolshevik ideas among the South Slavs, the continuities and discontinuities of Marxist thought before and after 1917, as well as the development of the concept of the Leninist right to self-determination in the context of the political situation in the Balkans in the post-WWI period.