The economic analysis of regulation is a broad topic, with implications for environmental protection, communications and technology policy, public health, immigration, national security, and other areas affecting risk and welfare in society. This chapter covers only a portion of the relevant ground, focusing on the following essential topics: First, what do we mean by “economic analysis” and what do we mean by “regulation”? Second, why has this topic become an important one, not only the United States, but in most advanced democracies? Third, why is economic analysis and regulation a contested, even contentious, aspect of modern regulatory activity? Finally, and most important, how is economic analysis structured into regulatory decision-making, and how might existing arrangements evolve over time?