Book of proceedings: Annual AESOP Congress, Spaces of Dialog for Places of Dignity, Lisbon, 11-14th July, 2017 ; Planning has to adapt itself to changing challenges and circumstances. But also innovative ideas and new ambitions from within can lead to changes of an established planning system. In Flanders (one of three Belgian regions), the administration of spatial planning is currently developing a new concept, format and approach: spatial ‘structure planning’ will be followed-up by ‘policy planning’. To foster flexibility, a new legal frame and instruments redirect planning towards combining a long-term strategic vision with mid-term realization-focused policy-frames. The regional government hopes to approve the new planning system by the end of 2017. Worth mentioning here is the shift from hierarchical relationships between planning levels to partnership-relationships based on equivalence. Collaboration at and between governance levels, policy domains, and relevant actors is central to this. The regional planning agency will provide rather guidance than norms. Since that kind of collaboration is not yet a structural part of the actual planning culture, this new direction is at odds with practices until now, and needs critical support. This paper has the ambition to assess the actual situation in Flanders and to contribute to theoretical positions on flexible planning within constellations of uncertainty, while developing concepts on collaboration and reframing concepts on participation. In terms of method, the recent ‘White Paper’ – approved November 2016 - about this ‘policy planning’, is scrutinized in the light of research findings from the Policy Research Centre (Steunpunt Ruimte: research by 3 universities for the administration Spatial Planning Flanders), i.e. conclusions from the research on methods for future explorations and collective learning for complex spatial issues (Kuhk, et al, 2016). This study analyses stimulating large-scale pilot practices, identifies crucial methodological issues and ...