The fourth report in the Global Environment Outlook (GEO) series from the United Nations Environment Programme (UNEP) provides a comprehensive, scientifically credible, policy-relevant and up-to-date assessment of, and outlook for, the state of the global environment. GEO-4 is published 20 years after the landmark World Commission on Sustainable Development report - Our Common Future - which was published in 1987. Environment for Development is the GEO-4 underlying theme and the report pays special attention to the role and impact of the environment on human well-being as well as to the use of environmental valuation as a tool for decision-making. GEO-4's specialist report, the Summary for Decision Makers is an essential guide for policy-makers. Both publications are excellent tools for teaching and research and relevant in the field of international environmental governance as they highlight policy opportunities for a more sustainable approach to development.