This report examines factors that have proven helpful in achieving the successful transfer of environmentally sound technologies (EST) to developing countries. It provides an overview of the main issues lying behind trade-related aspects of EST transfers. It then briefly examines the main channels for the transfer of such technologies and the factors which are relevant to technology transfer in general, and to EST transfer in particular. It concludes with a summary of conditions for successful EST transfers which seem to be particularly relevant in the context of trade. These include government regulation and marketbased instruments, trade-related policies and practices, intellectual property rights, capacity, and financing. The report is based on the extensive literature dealing with technology transfer in general, and EST transfer specifically, and on empirical work summarised in a range of case studies.