Beginning in the 1950s, a group of scholars primarily associated with the University of Chicago began to challenge many of the fundamental tenants of antitrust law. This movement, which became known as the Chicago School of Antitrust Analysis, profoundly altered the course of American antitrust scholarship, regulation, and enforcement. What is not known, however, is the degree to which Chicago School ideas influenced the antitrust regimes of other countries. By leveraging new datasets on antitrust laws and enforcement around the world, we empirically explore whether ideas embraced by the Chicago School diffused internationally. Our analysis illustrates that many ideas explicitly rejected by the Chicago School—such as using antitrust law to ...