The intermunicipal, cross-border co-operation in the European border regions has experienced a dynamic thrust of development in the last few years. This was facilitated by the changes in the political, legal and financial framework conditions, to which the community initiative INTERREG provided a considerable contribution. An additional factor in the Saar-Lor-Lux region is that subunits form in the actual border regions within the generously measured, regional work areas of the interregional co-operation, characterised by a fairy homogenous regional structure. Using three case examples, it is demonstrated that cross-border organisation structures have developed within these small regions on a municipal level. These are being institutionalised more and more. Using the regional development model of the network of cities, which is being discussed with regards to its cross-border applicability, we can in this context speak of local co-operation networks. In the case of the Agglomération Transfrontalière du Pôle Européen de Développement (PED) in the Belgian-French-Luxembourg state triangle, the participating local authority districts and government authorities have joined together to form an association and maintain a joint Observatoire de l'Urbanisme, responsible among other things since 1996 for the registration and processing of regional data as well as for the development of land use concepts. The M eeting of Mayors and/or the Ronde des Trois Frontières, responsible for the development of tourism in the German-French-Luxembourg Moselle Valley, are considerably less formal network structures. The co-operation between the border local authority districts was institutionalised in the Saar-Rosselle region in the form of the Intermunicipal Association for Work. The latter maintains a co-operation office with the Saarbrücken city association, principally responsible for co-ordination tasks with regards to current and developing, cross-border projects. Despite the depicted structural and legal impediments, an increased ...