Metropolitan regions and spatial deveolpment Academy for Spatial Research and Planning ; Pt. 4: Metropolitan regions as a new spatial planning concept : aspects of implementation using the example of South Western Germany Implementation of the metropolitan region concept in planning practice was the topic of a recent research project carried out at the university of Tübingen. Key questions include how this policy aimed at enhancing the competitiveness of metropolitan regions is implemented what opportunities it offers and what obstacles and challenges have to be overcome. The extensive empirical investigation presented here focuses on the actual implementation process in Baden Württemberg which presents a multi faceted implementation landscape with a variety of different approaches including the oldest and youngest generation of accredited metropolitan regions as well as cross border areas of influence. The analysis of surveys of community offi cials combined with extensive interviews with stakeholders and planning authorities provides insight into a dynamic process and highlights significant differences in planning and implementation practices. A considerable gap is revealed between planning theory and practice especially in terms of flexible geometries and metropolitan governance structures. The increasing discrepancy between functional and administrative territories has led to over extension trends as well as to fears of marginalisation. The envisaged concept of large scale communities of responsibility lacked transparency and credibility for actors in rural areas leading to fears of being left behind from the development in agglomeration areas.