Even though metropolitan areas account for half of the population, and an even larger share of economic activity of OECD countries, almost no systematic information on governance structures in these areas exists. This study – based on a novel data set – gives an overview of governance arrangements in OECD metropolitan areas. It shows that organisations dedicated to metropolitan area governance are common, but often have little powers. Nevertheless, the existence of such organisations is related with better performance on a range of important outcome variables, such as public transport systems, environmental issues, and urban sprawl.