Since the Rio Earth Summit in 1992, sustainability has emerged as an over-arching policy goal in the OECD Secretariat and in its Member countries. Real progress depends upon the integration of environmental and social goals with economic ones. This publication provides an overview and analysis of trends and identifies policy gaps and trade-offs that have been encountered and points to future options. The authors document positive trends which have emerged signalling greater sustainability, as well as areas where progress has proved more elusive. While the main focus is the OECD region, expanding linkages -- among all countries and regions -- form an important part of the story. The coverage of the volume reflects the OECD's diverse subject matter expertise, and some of the interdisciplinary synergies that the Organisation can generate. Part I of this two-part volume concentrates on socio-economic issues, including the integration of economics and environment; trade and environment; changing consumption and production patterns; assessing environmental performance; development co-operation; and the evolution of aid agencies since Rio. Part II takes an in-depth look at nine sectoral issues: energy; transport; agriculture; toxic chemicals; climate change; nuclear energy; urbanisation; biotechnology; and education. In short, this publication gives essential keys to meet the major challengeof the 21st century: helping to make sustainability a reality.