This article examines the writings of late 19th and early 20th-century Marxist theorists and political leaders from the Russian and Austro-Hungarian Empires and their influence on the chief Bolshevik theorist of Soviet nationality policies, Joseph Stalin. It argues that although many early Marxist theorists held divergent views on managing nationalism, they uniformly rejected biological or romantic spiritual conceptions of the nation and instead posited that nationalism and contemporary nations are relatively new, socially constructed phenomena arising from processes linked to economic and political modernization. These perspectives align with what contemporary academia labels as “modernist” theories of nationality and this analysis therefore challenges prevailing views on the genesis of these theories, tracing them back to early Marxist thinkers rather than late 20th-century Western European theorists such as Benedict Anderson and Ernest Gellner. This modernist understanding of nations as products of material forces and processes enabled socialists to envision steering nation formation. For the Bolsheviks and some of the later international revolutionaries they inspired, this meant that just as they believed they could accelerate the transition to a socialist future through active class management, so too they believed they could control and expedite the construction of national identities through carefully designed policies.