When it was first published a quarter of a century ago, Richard Posners exposition and defense of an economic approach to antitrust law was a jeremiad against the intellectual disarray that then characterized the field. As other perspectives on antitrust law have fallen away, Posners book has played a major role in transforming the field of antitrust law into a body of economically rational principles largely in accord with the ideas set forth in the first edition. Todays antitrust professionals may disagree on specific practices and rules, but most litigators, prosecutors, judges, and scholars agree that the primary goal of