Cooperation between diverse state, economic and civil society actors in urban society requires a comprehensive system of cooperation, systematic negotiation and joint decision-making. The social formation that best describes this system is a network. This presentation examines the network of sustainable urban development in Hannover under the premise that strong networking is essential for the realisation of sustainable goals in the city. Based on network theory we assume that especially actors (organisations and projects) at the interfaces of this network influence the quantitative strength and the qualitative orientation of the network. Are actors with a strong network at the interfaces of the network capable of determining the fate of the network from their position of power? Or do they understand their special position as assuming the responsibility of being representatives of interests and mediators of other network actors? The data for the quantitative network analysis were collected by means of an extensive standardised online survey among the actors of sustainable urban development in the City of Hannover. Actors were asked about their relations to cooperation partners in the context of sustainable urban development. Relationships were further differentiated according to symmetrical and asymmetrical relationships. In addition, the centrality of the actors in the network was surveyed and the existence and importance of sub-networks was investigated. Basically, it can be stated that municipal administrative bodies occupy the most important positions in the network. The actors are more closely networked when they are bureaucratically institutionalised, and they are less networked when they work flexibly as temporary projects and initiatives. Municipal institutions from the fields of environment and urban development in particular stand out here as controlling interface actors, while artistic-cultural initiatives in particular are more likely to need the help of other actors, mostly from the municipal administration. The result of a relative dominance of municipal interface actors, reflected in a transdisciplinary sense to the participants, was evaluated differently by the participants. In general, one can speak of a structure- or agency-oriented evaluation of the network results. On the one hand (structuralist-utilitarian interpretation) the dominance is critically regarded as a monopoly of power, since a dependence on interface actors could be exploited. On the other hand (culturalist-interactionist interpretation) the power of the interface actors is advocated, since out of them, with the agreement of all networked actors, the goals of sustainable urban development can be achieved even better. This discussion reflects well the current debate on the application of network theory for the city. Based on Harrison White's concept of community identity, it is assumed that a monopolistic exercise of power can be prevented by collectively agreed rules and values.