This project promotes building regional capacity by means of collaborative planning in order to co-evolve with change. It is not about weighting alternative solutions or leaving things to the market, but about cooperation between actors from the public, private and business sector, each with their own knowledges that can be employed to build adaptive strategies. The known, UK originating, planning instrument green belt has been used to make the case. The green belt policy aimed to keep land open and got developed in the UK in the first half of the twentieth century. In time it became an universal accepted means to control urban sprawl. During the last decade some fundamental changes within the object and process of spatial planning has complicated the very effectiveness of this spatial planning instrument. First metropolitan areas are growing together into a new phenomenon called metropolitan regions. Within these metropolitan regions green belts have become part of a spatial unit that also contains opposing land uses like urbanized areas, urban sprawl, and highly dense residential areas. Secondly within the process of spatial planning a shift from government to governance is fading the system responsible for the implementation of green belts. Governing processes are no longer fully controlled by government but subject to negotiations between a wide range of public, semi-public and private actors, whereas green belts are depending on a high level of intervention by government. A developed hypothesis responding to these fundamental changes has been tested and further explored in a case study: the case of the Green Heart. The Green Heart is a spatial policy for controlling urban growth in the central part of Randstad Holland. During the last decade Dutch national government is slowly retreating from this policy. At the same time the area is confronted with urgent local problems threatening the very characteristics of its cultural landscapes. The western part has to deal with soil salinazation, while the amount of fresh water storage is decreasing. In the eastern located peat lands the characteristic peat is vanishing as a result of oxidation. This process of oxidation is caused by low ground water tables needed for agriculture, without interfering the peat will be disappeared in 50 years. Proposing a collaborative planning strategy this project has found new ways to deal with these issues while simultaneously it does an effort to revisit the universal green belt planning instrument.