How can the environmental effects of trade liberalisation agreements be assessed ? Are available methodologies sufficiently tuned to current concerns? In order to take stock of the state of the art in assessment methodologies, the OECD organised a two-day technical workshop to focus on past practice and new tools for assessing the environmental effects of trade agreements. Some two dozen experts from governments, international organisations, universities international organisations, universities and NGOs active in this area presented lessons from past practice and results of the considerable advances made in recent years. This volume brings together the papers presented during the two-day workshop by the invited experts and the comments from a range of governmental and international organisation practitioners and representatives of civil society who participated in the workshop. In addition to the presentations on methodologies, this book includes the workshop rapporteur's summary of the gaps in the existing research in this field.