The capacity of the transmission network determines the extent of integration of a multi-national energy market. Cross-border externalities render coordination of network capacity valuable. Is it then optimal to collect regulatory powers in the hands of a single regulator? Should a common system operator manage the entire network? I show that optimal network governance depends on (i) whether the centralized regulatory agency is able to balance the interests of the different countries; (ii) asymmetries across countries in the gains from market integration; (iii) network characteristics (substitutability versus complementarity); and (iv) the social cost of operator rent.