This report explores the ways the World Bank and developing nations can reduce losses from collusion in procurement, fraud and corruption in contract execution. This draws on what the Preventive Services Unit of the World has learnt from its investigations and reports by borrowing country governments, and the experience of developed countries. The report begins with a review of the findings in 29 cases of misconduct in World Bank funded projects. It follows with an analysis of the incidence of collusion in procurement in non-bank projects and estimates of its impact on project prices. It also examines measures developed countries have taken to attack collusion and suggests how they can be adapted to the environment in developing countries.