Illegal trade in environmentally sensitive goods, such as threatened wildlife, timber, hazardous waste, and ozone-depleting substances, has been a long-standing issue in the international trade and environment agenda.  The nature of such illegal trade makes it difficult to fully understand its extent and impact on the environment.  Developing effective policies to reduce illegal trade requires a clear understanding of what drives this trade and the circumstances under which it thrives.  In this report, evidence-based on customs data and information from licensing schemes is used to document the scale of illegal trade, as well as the economic and environmental impacts of such trade.  National and international policies have an important role to play in regulating  and reducing illegal trade and the report highlights a range of measures that can be taken at both levels.