Decentralized systems were implemented in many developing countries in the 1970's after the failure of centralized systems. In general, it is hard for regency and municipality to execute their new decentralized responsibilities and authorities. They still have many difficulties and constraints due to human resources, revenue, infrastructure and overall management capacity to handle the decentralized responsibility and the accompanying authority. Having a regional cooperation would be a good way to achieve efficiency and effectiveness. Kartamantul, a cooperation of three local governments, becomes popular in Indonesia because of its success in doing regional cooperation to provide well-improved quality of service provision. After almost ten years it manages seven projects of urban infrastructure. Nowadays to face globalization era, improving capacity building of Kartamantul is needed to get more creative and innovative cooperation. Metropolitan governance becomes an important issue to find a better structure of regional cooperation. This book explores what do Kartamantul have and should be had towards a metropolitan region using theories and models of metropolitan region.