From the end of the 1990s onwards, German spatial planning experiences have been enhancing the value of the notion of Region as a key tool in “bottom-up spatial planning” ; thus moving on from Raumplanung (spatial planning) to Raumentwicklung (spatial development). However, the region remains ambivalent, prevailing. But on the other hand, the need to go back to the notion of territory is still felt, if not always accepted, by local actors. The region would first be used as a deterritorializating device at the stage of regional development projects, before being turned into a reterritorializating tool afterwards, when implementing actions and projects. I will use a few national (German) and regional examples (the spatial planning region of South-West Thuringe) to illustrate these ideas. standing as it is between territories and networks, formal and informal structures. There are two identifiable types of regions in Germany : the region as defined by spatial planning and the region in general. The first one (Raumordnungsregion when applied to the Bund, and Planungsregion when applied to the Länder) is an external planning instrument, thus coordinating local actors and their projects. This is grounded upon the territorial divisions within each Land. Regions in general (Region) are spaces intended for local action, founded upon reticular patterns of cooperation rather than upon territorial ones, such as urban networks, regional development concepts, etc. But local/regional development rests upon these two interweaving/interacting entities. The play on scales and the ambivalent relations between networks and territories in regional development are at the core of this article. Eventually, this leads us to a paradoxical form of dynamism. On the one hand, the dismissal of territorial rigidity and the choice of weak, thematic and reticular cooperation seem to be prevailing. But on the other hand, the need to go back to the notion of territory is still felt, if not always accepted, by local actors. The region would first be used as a deterritorializating device at the stage of regional development projects, before being turned into a reterritorializating tool afterwards, when implementing actions and projects. I will use a few national (German) and regional examples (the spatial planning region of South-West Thuringe) to illustrate these ideas.