For the past two decades, the Antitrust Guidelines for the Licensing of Intellectual Property have explained how the Department of Justice’s Antitrust Division and the Federal Trade Commission evaluate licensing and related activities involving patents, copyrights, trade secrets and know-how. The Guidelines have played a key role in the department’s investigative and enforcement efforts and guided businesses and courts, having been cited in numerous opinions and government briefs. The principles espoused in the original Guidelines continue to be sound. Nevertheless, developments since 1995 prompted us to undertake the process of modernizing them to reflect changes to the law, as well as the agencies’ recent enforcement and policy experience.