What is regulation? Under what circumstances is it needed? What forms should it take? Such questions are especially relevant at a time in United States history when governmental involvement in decisions formerly left to individuals and business firms evokes concern on all sides of the political spectrum. In Going by the Book, Eugene Bardach and Robert A. Kagan address these questions and provide richly detailed descriptions of the dilemmas of enforcement in a broad variety of regulatory programs. The authors argue that the most successful forms of regulation emerge from a flexible rather than a legalistic method of implementation. Relying on extensive interviews with government agency officials and regulated businesses, they find that American techniques of regulation, by their very nature, frequently generate "regulatory unreasonableness," that is, governmental requirements that seem sensible in principle but that make little sense in particular situations. By exploring the roots and dynamics of regulatory unreasonableness and the ways in which some regulatory officials and programs avoid it, Going by the Book simultaneously illustrates the virtues of flexible regulatory enforcement and illuminates the political and practical obstacles to achieving that goal. In their new introduction, the authors discuss their findings in light of the twenty years that have passed since Going by the Book was first published. They explore the growth of regulation in recent years as well as many reforms, noting that while much has changed, much has not. They argue the United States remains torn between two competing visions of regulation: enforcing laws versus solving social problems. Thus, the deep insights into the regulatory process that Going by the Book provides continue to make it a mandatory work for public policymakers, experts in economics, government, and regulatory law, and students and teachers of political science, public policy, and sociolegal studies.