LEDA is a research project to study legal and regulatory measures to promote sustainable transport in cities. The scope is encompassing measures in the transport sector, but also in related sectors influencing transport demand and supply like environment and land-use planning. The focus is on passenger transport. All kinds of legal and regulatory measures concerning urban transport and related areas are included in an inventory of measures that are currently being applied in a selection of 40 European cities. About 20 of the most innovative, effective and less well-known measures are analysed in depth. Research includes aspects like public responses, enforcement requirements and aspects related to accompanied measures. A tempting framework to analyse the transferability of the measures is established. Much effort has been undertaken to derive guidelines for the urban authorities on how to implement the most effective measures as well as recommendations for the regional, national and European authorities, indicating the possible changes in the legal framework. The instruments to support the dissemination of the results are a web site, a CD-ROM with the database, brochures, an international conference and round table conferences in each partner country in order to initiate a debate on the appropriateness of changing the legal frameworks. The whole process is accompanied by four Regional User Groups, which together cover all the Member States and CEEC countries.