Recent decades have seen a considerable increase in delegation to independent regulatory agencies, which has been justified by reference to the superior performance of these bodies relative to government departments. Yet, the hypothesis that more independent regulators do better work has hardly been tested. We examine the link using a comprehensive measure of the quality of work carried out by competition authorities in 30 Organisation for Economic Co-Operation and Development (OECD) countries, and new data on the design of these organizations. We find that formal independence has a positive and significant effect on quality. Contrary to expectations, though, formal political accountability does not boost regulatory quality, and there is no evidence that it increases the effect of independence by reducing the risk of slacking. The quality of work is also enhanced by increased staffing, more extensive regulatory powers, and spillover effects of a more capable bureaucratic system.