This article spells out the significance for Development Theory of the idea of Buneven and combined development.^It argues that the impasse that afflicted materialist theories of international capitalist development in the 1980s was rooted in two fundamental problems: a misreading of Marx's categories as directly historical; and the lack of an orienting method for deploying those categories to interpret a world of multiple and interacting societies. After reviewing the impact of these problems on the evolution of the main postwar approaches to development, the article undertakes the task of reconstruction in three steps. First, it sets out Marx's understanding of capitalist modernity, showing how this calls for but does not explicitly provide a historical conceptualization of capitalist development. Second, it shows how Trotsky's idea of Buneven and combined development^offers such a conceptualization, and how it thereby historicizes the phenomenon of development itself. Finally, it considers the limits of Trotsky's own formulation of the idea, and suggests how a version released from these limits could better explain the complex spatio-temporality of capitalist development and constructively engage the most consequential challenges posed by ascendant cultural approaches in the field.