The European Commission’s DG Competition has published an independent report on quantifying antitrust damages by Oxera and a multi-jurisdictional team of lawyers led by Dr Assimakis Komninos, with economic assistance from Dr Walter Beckert, Professor Eric van Damme, Professor Mathias Dewatripont, Professor Julian Franks, Dr Adriaan ten Kate and Professor Patrick Legros. Enforcement of the European competition rules continued at a steady pace during 2009, with total fines amounting to €1.6 billion in six price-fixing cartels. However, fines are not the end of the story for infringers of competition law because customers and competitors can also claim compensation before a national court. The Commission has promoted private actions for damages by victims of competition law and there has been an increase of such actions in courts across Europe. However, the lack of clarity on how to quantify damages in such actions can be a practical barrier. One of the obstacles to damages actions is the uncertainty over the quantification of the harm suffered—which types of method are acceptable? What methods are feasible? What is best practice for estimating damages? This economic and legal study published today is a step towards such guidance.