This paper estimates the impact of competition policy on total factor productivity (TFP) growth for 22 industries in 12 OECD countries over 1995-2005. We find a positive and significanteffect of competition policy as measured by newly created indexes. We provide results based on instrumental variables estimators and heterogeneous effects to support the causal nature of the established link. The effect is particularly strong for specific aspects of competition policy related to its institutional set up and antitrust activities. It is also strengthened by good legal systems, suggesting complementarities between competition policy and the efficiency of law enforcement institutions.