The development of metropolitan regions shows increasing patterns of polycentrism, with growing relevance of small and medium-sized municipalities, suburbs and outskirts, which become economic subcentres within enlarging metropolitan realities. Nevertheless, governance analysis has focused primarily on the role of central cities or on the metropolitan region as a whole. This article focuses on the social configuration of small and medium-sized municipalities as collective actors and their role in the emergence of polycentrism. The article analyses how the economic, political and social hegemonic actors in these cities organise innovative strategies to ensure the centrality of their area in the metropolitan region presenting the analysis of two areas in two European metropolitan regions; the Black Country in the West Midlands conurbation (United Kingdom) and the Vallès Occidental area in the Barcelona Metropolitan Region (Spain). In both areas, innovative forms of governance oriented towards local economic development and social cohesion have emerged involving municipalities, chambers of commerce, trade unions and third sector actors. Beyond the implementation of local policies these forms of governance reinforce specific scales for economic agglomeration to reinforce subcentrality of certain municipalities. The analysis of these cases shows that there are dynamics of competitiveness and collaboration within metropolitan regions in which subcentres are trying to compete with the central city and but at the same time taking profit from the overall metropolitan strategy in the global arena.