This paper analyses the nature and intensity of the functional and institutional integration in three cross-border metropolitan regions in Europe: Basel, Geneva and Luxembourg. Results show that there is not necessarily a reciprocal link between the size of the functional area and the extent of the cooperation. Whilst no metropolitan-sized organisation is on the agenda in Luxembourg, the cases of Basel and Geneva show that the presence of a national border offers an opportunity to invent original forms of governance, increase the autonomy of the local authorities by different types of cooperation which transcend the institutional and territorial divides, and promote the international character of the metropolitan centre. In a context of global competition, these features represent an undeniable benefit.