Sociologists have noted that the ideological inclusiveness of nationalism varies. By comparing the Bolshevik and Chinese communist revolutionary elites, this article explains that such variation depends on the social strength of nationalism. A strong nationalism is (a) undergirded by a widely diffused national culture that can socialize most radical elites into the nation; (b) kept institutionally open to broad social strata so that lower classes can form a nationalist identity through participation; and (c) universally believed to be a geopolitically feasible anti-colonial revolution so that radical elites can think of engagement as worthwhile and necessary. Using a comparative biographical method probing both nationalists and communists, this article demonstrates that nationalism in Tsarist Russia was far weaker than in post-imperial China. In the former, the nationalist movement excluded communists while, in the latter, communists were incorporated. Therefore, the two communist parties had different understandings of Marxism.