In the context of a growing emphasis on research and application of citizen engagement methods in environmental planning and management (e.g. Reed 2008; Von Korff et al. 2010), we compare three collaborative activities aimed at finding innovative coastal policy solutions in the Netherlands. In these activities, participants across the citizen, science and policy divide were involved in designing nature-based interventions for specific areas in the Netherlands. The activities are compared in terms of the theoretical promise stakeholder engagement holds for influencing participants' understanding of the respective bio-geophysical systems, the actor networks and for effecting knowledge sharing. We find local knowledge offers the potential for crafting coastal policy solutions to fit the specific bio-geophysical and societal context. The empirical analysis revealed the deep competence of local people, who generally understand their lived environment in a systemic way, and the knowledge that can be harvested to broaden and enrich the design space for coastal solutions – in addition to a willingness on the part of the stakeholders to collaborate in developing local solutions for sustainable futures. Although measures to reduce power differences and enable local knowledge inclusion served to broaden the design space for innovative solutions in our case studies, they also constrained the scientific and technical quality of the contributions from professional experts such as bio-geophysical scientists, engineers, spatial planners and policy analysts. As such, future work addressing the dilemma of integrating high quality professional inputs into coastal policy solutions founded on local expertise is advocated. [ABSTRACT FROM AUTHOR]