In the framework of a critical illustration of the contemporary history of economics, this chapter provides an assessment of the development of microeconomics since von Neumann’s and Morgenstern’s theory of expected utility, including the developments of general equilibrium theory, reproposals by the Chicago school and others of the Marshallian theory, Samuelson’s Marshallian-Walrasian synthesis, the new theories of the irm (oligopoly and barriers to entry, contestable markets and others), growth and limits of game theory.