Foucault’s concept of ‘biopolitics’ has sparked a lively debate within critical theory, although Foucault himself rarely used it after The History of Sexuality, Volume 1. In this chapter I argue that the reasons both for the way ‘biopolitics’ stirred Foucault’s readers and for his subsequent abandonment are to be found in the relation between Foucault’s model of critique and the role ‘biopolitics’ plays in it: it names the counter-truths derived from Foucault’s critical diagnosis of the dispositif of sexuality. Since ‘biopolitics’ was introduced as a notion with a specific critical function closely tied to Foucault’s model of critique, I first explicate this model of critique as a diagnostic practice of prefigurative emancipation before re-reading Le Volonté de Savoir from this methodological perspective. After Le Volonté Savoir, Foucault tried turning ‘biopolitics’ into a descriptive term, no longer naming the critical diagnosis but the object to be criticised. Yet within Foucault’s model of critique, this required him to produce a new critical diagnosis which he never did. The implication for contemporary usages of ‘biopolitics’ in critical theory is that it either needs to develop its own counter-truths from a critical analysis of biopolitics or use a different model of critique.