Drawing on historian and philosopher Michel Foucault, this chapter demonstrates the particular role of early neoclassical economics between the 1870s and 1920s, and public choice theory throughout the second half of the 20th century in the constitution of neoliberal governmentality. Foucault examines how classical political economy and neoliberal economics developed two versions of liberalism. However, he mentions early neoclassical economics in a scattered and sparse manner and does not touch upon public choice theory as part of the developing neoliberal governmentality at all. The main argument is that an overall historical understanding of neoliberal governmentality can be achieved by pondering the radical modifications of classical liberalism by early neoclassical economics towards neoliberal governmentality and, by extension, the subsequent comprehensive modifications carried out by public choice theory. The method of this chapter relies on Foucault’s analytics of power/government, nominalist method, and genealogical history of ideas. This chapter will conclude that the governmentality-based analysis of early neoclassical economics, public choice theory concerning their related theoretical and discursive tools, and political reason prove to be the complement to the new lines of the Foucauldian critique of neoliberal governmentality.