Trade has increased as a share of the economy for several years, but U.S. companies can face difficulties competing in foreign markets when countries apply different regulatory requirements to address similar health, safety, or other issues. GAO was asked to examine what U.S. agencies are doing to engage in international regulatory co-operation. This book provides an overview of U.S. regulatory agencies' international co-operation activities; examines ways that U.S. agencies incorporate outcomes from international regulatory co-operation activities and consider competitiveness during rulemaking; and examines factors identified by U.S. agencies and stakeholders that act as facilitators or barriers to international regulatory co-operation.