At the 1992 United Nations Conference on Environment and Development, popularly known as the Rio Earth Summit, the world's leaders constructed a new "sustainable development" paradigm that promised to enhance environmentally sound economic and social development. Twenty years later, the proliferation of multilateral environmental agreements points to an unprecedented achievement, but is worth examining for its accomplishments and shortcomings. This book provides a review of twenty years of multilateral environmental negotiations (1992-2012). The authors have participated in most of these negotiating processes and use their first-hand knowledge as writers for the International Institute for Sustainable Development's Earth Negotiations Bulletin as they illustrate the changes that have taken place over the past twenty years. The chapters examine the proliferation of meetings, the changes in the actors and their roles (governments, nongovernmental organizations, secretariats), the interlinkages of issues, the impact of scientific advice, and the challenges of implementation across negotiating processes, including the Framework Convention on Climate Change, the Convention to Combat Desertification, the Convention on Biological Diversity, the Commission on Sustainable Development, the UN Forum on Forests, the chemicals conventions (Stockholm, Basel and Rotterdam), the Montreal Protocol on Substances that Deplete the Ozone Layer, the Convention on International Trade in Endangered Species, the Convention on Migratory Species and the International Treaty on Plant Genetic Resources for Food and Agriculture.