By the end of the 80s the shift in emphasis in forestry development towards social and environmental concerns had added complexity to forestry sector and project work. but it had not diminished the importance of a solid economic base. It was felt that the earlier publication needed to be checked both against new developments in project economics analysis and against the practical experience acquired in analysing the economic impacts of forestry projects over the decade. This concern was formally expressed by the Committee on Forest Development in the Tropics at its Ninth Session in September 1989 when it requested FAO to undertake an in-depth revision and updating of Paper No 17. The present publication complies with this formal request. It also reflects the concern shared by FAO , UNEP and the World Bank that the scope of forestry project assessment be broadened to focus on impacts which translate effectively the role of forestry in sustainable development. This new publication is, in fact, part of a collaborative effort between the three Organizations to develop more holistic approaches to assess the economic, social and environmental impacts of forestry projects as a measure of their contribution to sustainable development. The publication is proof of this common effort and reflects a combination of the perspectives and experiences of the three Organizations. It is hoped that the impact assessment approaches recommended will be widely adopted as practical guidelines.