On the surface there is agreement, sustainable development refers to a broad set of issues, going beyond the relationship between the economy and the environment to encompass human and social concerns. Scratch the surface and you open a Pandora's box of differing notions of sustainability and means of achieving it. How can progress towards sustainable development be measured then? The major difficulty in developing indicators to track progress towards sustainable development is not the lack of data but rather the lack of frameworks to organise and synthesize existing information. This volume brings together a number of approaches to this question pursued in academia, national administrations and international organisations, as presented at an expert workshop held at the OECD headquarters in September 1999. These approaches include developments of the traditional national accounts system, construction of synthetic measures of sustainability such as "genuine savings", physical measures of material flows, and selections of indicators based on variants of the "pressure, state, response" model. This volume also reviews a number of initiatives undertaken within the OECD to monitor trends in the sustainability of specific sectors and sub-national areas.