I decided to write this book after a personal incident that took place more than a decade ago—with which I begin the introductory chapter.I was living in Seattle at the time. One evening the doorbell rang and it was an environmental volunteer asking for contributions for his organization. I wasn’t a big fan of his NGO, so I declined and when he asked why, I said that I disagreed with some of his organization’s positions. He asked which ones and I responded, “Norwegian whaling.” After an inconclusive debate about the status of minke whales in the North Atlantic, the volunteer, in frustration, played his trump card, exclaiming, “I suppose it doesn’ t matter to you that Norway is in violation of international law!” That really got me going, so I replied—somewhat pedantically—that I happened to be a professor of international law and that, as a legal matter, Norway is in compliance with the International Whaling Convention. He stomped off in search of greener pastures.I found the encounter fascinating because it illustrated so many themes in international environmental law: the intertwining of normative and factual disputes, the special status of legal argumentation, the various design features of international agreements. And I got to thinking, what could a person read to get a broad, realistic, pragmatic overview of the field, which synthesizes the range of work in different disciplines on international environmental problems? I couldn’t think of anything and decided to write this book.