The purpose of this book is to review and analyze the period (roughly from the 1950s to the present) when the environment became an issue as important as economic growth, or war and peace; to assess the current situation, and begin planning for the challenges that lie ahead. Most people are aware of both the environmental destruction taking place around the world and of the specter of climate change. The devastation of New Orleans by hurricane Katrina illustrates the potential for disaster when climate change is combined with the mismanaged environmental policy. How did we get tot his point? What has been done and what can be done to avoid future environmental disasters? Thirty-two contributing chapter authors (among them, one of the principal drafters of the National Environmental Policy Act, Chief of the African Environment Division and the World Bank, Vice President of the Center for Conservation Innovation at the World Wildlife Fund, President of the Zoological Society of London, former President of the Ecological Society of America) use their unique, authoritative perspective to review the evolution of environmental science and policy in the past half century. Each author describes the evolution of environmental science and policy in the past half century and consider the challenges of the future. Although the authors of this book com from various fields, they have followed paths that have generally converged on the concept of sustainability. This book attempts to define what sustainability is, how we can achieve it, and what the prospects for sustainability in the future are.