During the 1990s, US antitrust policy began to take greater account of economic theories that emphasize the critical role of innovation and change in the competitive process. Several high-profile antitrust cases have focused on dynamic innovation issues as much as or more than static economic efficiency. But does dynamic competition furnish a new rationale for activist antitrust, or a new reason for government to leave markets alone? In this volume, more than a dozen leading scholars with extensive antitrust experience explore this question in the context of the Microsoft case, merger policy, and intellectual property law.