This paper estimates the impact of competition policy on total factor productivity growth for 22 industries in twelve OECD countries over 1995 to 2005. We find a positive and significant effect of competition policy as measured by 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 setup and antitrust activities. It is also strengthened by good legal systems, suggesting complementarities between competition policy and the efficiency of law enforcement institutions.