Environmental protection constitutes the most ambitious regulatory commitment in the United States (and most capitalist democracies). It also constitutes one of the most interesting topics for policy and political analysts for several reasons. First, the policy is inherently complex. It requires the integration of rapidly evolving bodies of scientific and social scientific research. Second, the policy is inherently expensive. Mitigation and control impose large costs on businesses, creating powerful incentives for mobilization and forcing officials to place a greater emphasis on the costs and benefits of their actions. Third, the policy is increasingly challenged by new problems, both domestic (e.g., the intersection of civil rights and environmental policy) and global (e.g., climate change and sustainable development). Reflecting these factors, environmental protection has been under transition for several decades as policymakers search for new innovations in policy and institutional design. This seminar will explore environmental regulation in the United States. In addition to providing a comprehensive overview of core policies, we will explore several topics including the philosophical foundations of environmentalism; the factors shaping political mobilization in support of and in opposition to policy; the difficulties encountered by bureaucratic agencies in managing scientific and social scientific complexity; the efforts to develop innovative approaches to regulation; and the challenges posed by a number of global environmental problems. Although the seminar focuses on environmental protection in the United States, we will draw on examples of environmental regulation in a number of other nations.