The past decade has been a time of great upheaval for transatlantic competition policy. This is evident in the United States (at the federal and state levels), the European Union, and the United Kingdom. With the reinvigoration of antitrust policy has come a reinvigoration of antitrust economics, which has been increasingly prominent in the reasoning of regulators and courts. This volume chronicles key flashpoints in this process, from an economics point of view. It provides 18 contributions from leading antitrust economists involved in recent groundbreaking merger, monopolization, and anticompetitive-agreement cases on both sides of the Atlantic. In all instances, the basic economic features of these important cases should be accessible to all readers who have an interest in antitrust.