This chapter reconstructs Marx’s concept of the “alienation of labor” as a structurally ambiguous expression, whose genitive-subjective and genitive-objective readings have been flattened by traditional accounts of a unified “theory of alienation”. It first distinguishes these two readings and proposes a genitive-objective interpretation, according to which “alienated labor” names a historically specific mode of existence of modern economic relations rather than an underlying human essence. The chapter then reexamines the Manuscripts of 1844 to show how the concept of alienation emerges from a metacritique of political economy and designates the inverted, phantasmagoric forms in which commodity-producing labour appears as wages, profit, rent, and capital. A subsequent analysis of The Holy Family demonstrates how Marx’s engagement with Proudhon and Bauer deploys alienation to think capitalist society as a contradictory whole, to criticise external, normative models of critique, and to locate “practical debasement” in the compulsory character of wage labour. The discussion of German Ideology argues that Marx and Engels displace anthropologising, philosophical uses of “self-alienation” by restricting the concept to the practical-material “modes of existence” of private property, social power, and division of labour. Finally, the chapter reframes alienation within the framework of Marx’s first critique of political economy, claiming that the growing primacy of genitive-objective readings underlies the later critique of fetishism by treating capitalist categories as “objectivities without object” and rejecting any realist semantics of a transhistorical human essence.