Metropolitan areas are centres of economic activity and home to half the population within the OECD. Due to their socio-economic complexity, policies in metropolitan areas are highly interdependent on each other. In this context, it is crucial to find the governance arrangements that take these interdependencies into account. Empirical analyses show that the choice of governance arrangements has important consequences for economic performance, for the well-being of citizens and for environmental outcomes in metropolitan areas. The better governance arrangements work in coordinating policies across jurisdictions and policy fields, the better the outcomes along the abovementioned dimensions. Coordination of policies is especially important in light of the often outdated municipal borders in metropolitan areas that do not correspond to today’s functional realities. This mismatch contributes to coordination problems and increases the need for governance structures that compensate for it.