That the idea of world revolution was crucial for the Bolshevik leaders in the years following the 1917 revolution is a well-known fact. But what did the party's rank and file make of it? How did it resonate with the general population? And what can a social history of international solidarity tell us about the transformation of Soviet society from NEP to Stalinism? This book undertakes the first in-depth analysis of the discourses and practices of internationalism in early Soviet society during the years of revolution, civil war and NEP, using forgotten archival materials and contemporary sources.