How can we meet the needs of today without diminishing the capacity of future generations to meet theirs? This is the central question posed by "sustainable development". OECD countries committed themselves to sustainable development at the 1992 UN Conference on Environment and Development in Rio, yet - almost ten years later - progress accomplished remains partial and uneven. Drawing on analysis carried forward in response to a mandate from OECD Ministers in 1998, this report stresses the urgency to address some of the most pressing challenges for sustainable development. It reviews the conceptual foundations of sustainable development, its measurement, and the institutional reforms needed to make it operational. It then discusses how international trade and investment, as well as development co-operation, can contribute to sustainable development on a global basis, and reviews the experience of OECD countries in using market-based, regulatory and technology policies to reach sustainability goals in a cost-effective way. The report also provides an in-depth analysis of policies designed to address key threats to sustainability in the areas of climate change and natural resource management, as well as of those that respond to sustainability concerns at the sectoral and sub-national level. The common thrust of the report is that substantial opportunities exist to make economic growth, environmental protection, and social development mutually reinforcing.