How and why do international environmental norms arise? In what ways do they affect behavior? Do they change what states and individuals actually do, and, if so, why? How effective are they in solving international environmental problems? These are some of the questions I examine in The Art and Craft of International Environmental Law.The book has several defining features. First, it focuses on the processes by which international environmental law is developed, implemented, and enforced, rather than on the substance of international environmental law itself. Accordingly, it is organized thematically, with chapters on such topics as the causes of environmental problems, obstacles to international cooperation, the design of international agreements, policy implementation, enforcement, and effectiveness. Process issues have received increased attention in recent years but have not yet received a book-length treatment. The Art and Craft of International Environmental Law aims to fill that gap.Second, the book is multi-disciplinary. To understand the international environmental process, we need to consider not only law, but also political science, economics, the natural sciences, and, to a more limited degree, philosophy, sociology, and anthropology.Third, the book is theoretical in its orientation, but tries to ground its discussions of theory through the use of concrete examples. In a wonderful book entitled Nuts and Bolts for the Social Sciences, Jon Elster wrote that his subtitle might have been “Elementary Social Science from an Advanced Standpoint.” That has been my goal as well: to write an elementary book from an advanced standpoint, with a stronger methodological and philosophical orientation than is typical in an introductory work.Finally, the book aims to be pragmatic, reflecting my experience working on international environmental issues as a U.S. government negotiator, adviser to non-governmental-organizations, and U.N. consultant. It tries to provide a real-world perspective on how international environmental law works—and sometimes doesn’t work. Students and scholars of international law fall along a spectrum, from true believers at one end to complete cynics at the other. My book seeks to chart a middle course. It reflects a degree of skepticism about some of the more visionary claims regarding the role of international environmental law. But it does not throw out the baby with the bath water. Rather, it seeks a realistic understanding of both the role and the limits of international environmental law.