Antitrust is the modern variant of the subject most commonly known as industrial organization and most commonly found in court rooms. This book brings together a selection of articles which discuss the role of economists in the enforcement of antitrust law (including the reverse effect on economists of their involvement with antitrust). It presents an idea of the various ways economists function in the world of antitrust, bringing experience to bear on the subject. The book includes not simply academic analysis of industrial organization but also works on dozens of antitrust legal proceedings.