First, it reviews different configurations of governing transport and spatial planning in OECD metropolitan areas. It then discusses possible institutional arrangements to achieve more effective integration between transport and spatial planning. While there is widespread consensus that better connecting transport and spatial planning decisions helps prevent costly consequences of urban sprawl and promotes harmonious development, institutional barriers remain slow to dismantle and co-ordination mechanisms put in place on an ex post, ad hoc basis may take time to become fully effective. The responsibility for transport planning and spatial planning occasionally lies within the same institution, but more often within different entities, as illustrated in the experience of the different case study regions (Table 2.1).