The Chicago School of antitrust has benefited from a great deal of law office history, written by admiring advocates rather than more dispassionate observers. This essay attempts a more neutral stance, looking at the ideology, political impulses, and economics that produced the Chicago School of antitrust policy and that account for its durability. The origins of the Chicago School lie in a strong commitment to libertarianism and nonintervention. Economic models of perfect competition best suited these goals. The early strength of the Chicago School of antitrust was that it provided simple, convincing answers to everything that was wrong with antitrust policy in the 1960s, when antitrust was characterized by over-enforcement, poor quality e...