This article examines Michael Hardt and Antonio Negri's and Paolo Virno's use of Michel Foucault's notions of 'biopower' and 'biopolitics' with respect to today's hegemony of immaterial labor, i.e. work without an end product. In spite of relatively infrequent references to work, Foucault formulates these notions in markedly economic terms: biopower is inextricable from work because, unlike punitive power that represses and disciplines life, it cultivates life by fostering an efficient, productive and active population. Drawing attention to a shift in emphasis in Hardt and Negri's and Virno's accounts of work and biopower -from a diagnostic analysis of labor practices to immaterial labor's latent political possibilities -it is argued in the article that what gets lost in this shift is Foucault's insistence on questioning the role of work in modern society. Work is not an inherently valuable activity, but, as current contradictions that have emerged with immaterial labor demonstrate, a product of mechanisms which endow it with its present status as the central organizing principle of both social and personal life.Michel Foucault's notions of 'biopower' and 'biopolitics' have had enormous impact on our understanding of how modern power operates. This article examines Foucault's later texts in which these notions are developed, paying particular attention to how he links them to changes with respect to work and economy. The first part of the article discusses how changes in the perception of the human body, health and disease that took place in the late eighteenth century affected new policies regarding hygiene, demography, sexuality and circulation of human resources. Together with other changes that pertained to work more directly (e.g. loans, saving funds, reforms in education), these policies were part of larger biopolitical changes that transformed modern society along the lines of economic efficiency and productivity. The second part turns to recent changes in global economy and patterns of work. Centered on Michael Hardt and Antonio Negri's and Paolo Virno's conceptualization of today's hegemony of immaterial labor (that is, work that results in no material or durable commodity), this part discusses the increasing value of cooperation and communication in contemporary labor practices, the progressing erasure of work's temporal and spatial boundaries, and the alleged greater autonomy and creativity of workers. The third part returns to Foucault to consider Hardt and Negri's and Virno's application of his notions of biopower and biopolitics on immaterial labor. Raising the issue of immaterial labor's contradictions that have been either omitted or downplayed by Hardt and Negri and Virno, this part questions the latter's optimism and shift of focus to immaterial labor's latent political potential because this shift disregards the main thrust behind Foucault's notions: work is not intrinsically valuable -its central role in modern society is a result of power mechanisms that have made it into something socially v...