Current EU cooperative systems projects like CVIS, SAFESPOT & COOPERS have demonstrated technical feasibility and positive user acceptance of cooperative mobility services.In the In-Time project common traveller information services based on distributed regional data sources accessible via one commonly agreed data interface have been developed.These common mobility services include dynamic navigation and intermodal routing and advice in real time but deliver no information from the traveller to traffic management.This is the scope of Cooperative Cities, which closes the "feedback loop" of cooperative mobility services and hereby elaborates a developement path for traffic management in European cities.Cooperative cities is based on the principle of co-modal transport information services which are coherent with the overall policy strategy and at the same time adaptive to changing dynamic traffic conditions and interactive with travellers.The starting point for cooperative cities technologies is the current status of available mobility information services with high quality data and information and the connection to the mobile users via UMTS/short range media (e.g 802.11p) to the navigator or the smartphone of the user. The cities involved inform the user in a fast, precise and accurate way of the changes in the status of the network and the possible consequences for travel times and connections.Following this approach the cities set up a mobile reference platform for the testing and validation of cooperative traffic information services and combine this with a service evaluation framework for the mobility services.The cities and regions have the possibility to compare their validation experiences with the collected feedback from the user communities of the mobility services.The further communication of best practices between cities is complementary to this work and leads to the definition of a deployment road map for cooperative services in cities.