This book draws upon an INTERREG III B CADSES project titled "Regional Integration and Metropolitan Development in Southeastern Europe", known with the acronym RIMED, setting forth its most important elements, findings and results. The aim of the project has been to promote economic development and regional integration in Southeastern Europe (SEE) on the basis of a synergic action which advances both trans-national networks of cooperation between metropolitan cities and strong city-region spread effects. Focusing on the case studies of Skopje, Sofia, Thessaloniki and Tirana, the project first shed light on the forces and processes that affect development prospects in SEE, providing a richer understanding of the problems, challenges and opportunities the metropolitan areas in the region are facing. Building on this basis, it was then made possible to specify a set of policies according to which economic development, international cooperation and spatial cohesion in the area can be promoted. In order to meet itς objectives, the project made use of a range of data sources and research methods. In particular, it analyzed secondary data, acquired from international, national and local sources, and primary data, collected through questionnaire surveys and interviews with key local actors. Furthermore, the findings and the subsequent policy recommendations have been discussed and refined in workshops as well as national and international conferences.