This article examines the late medieval Flemish urban network through the daily contacts between cities. This kind of research expands previous rather static research on urban networks. The central focus of this article is the extent of influence of information circulation on the development of urban networks. Firstly, the nature and speed of communication were examined. Secondly, a typological analysis of the list of messengers made possible an examinination of the cities' motives for sending them out. Who did the city approach in order to further its ends? Finally, the importance of rumours was analysed. The circulation of such informal information was actively incorporated into official urban communication, but not without due supervision. Rumours, we argue, effectively influenced urban politics.