This essay seeks to make a contribution to scholarship on the relation between Canguilhem and Foucault through the concept of milieu. It argues that Canguilhem’s work on the milieu was inspired by Uexkull and became the eventual means by which Foucault was able to theorize biopower. For both Foucault and Canguilhem, culture is to be understood as an extension of biology, constituting a “semantic milieu.” Though indebted to Canguilhem in this respect, Foucault’s theorization of biopower breaks with his understanding of society. The essay exemplifies this via a discussion of regulation and cybernetics, where Canguilhem is found to oppose the very possibility of a cybernetic society and Foucault is said to allow for one via his notion of governmentality. While Canguilhem turns out to be committed to a more humanist ideal of free will, in his theorization of biopower and governmentality, Foucault turns out to be more interested in analyzing the way freedom is deployed in liberal societies as an instrument of control.