The ARCH research project “Architecture and roadmap to manage multiple pressures on lagoons” aims to develop participative methodologies in collaboration with policy makers, local authorities and stakeholders to manage the multiple problems affecting lagoons (estuarine coastal areas). These areas represent ecosystems that are very vulnerable for climate change, increasing urbanisation and industrialisation. A central feature of ARCH is to provide realistic solutions to manage these pressures and establish a better connection (the arch) between science and policy. This is accomplished by facilitating the transition (i) from segregated disciplinary scientific results to well integrated and usable scientific knowledge, (ii) from “government” and sectoral policies towards “governance” and sustainable management; and (iii) from an unaware and uninformed “lagoon community” towards an involved and well-informed community. ARCH will work with 10 case study lagoons and estuaries having a geographical distribution covering all major seas surrounding Europe. A participatory workshop methodology will be used at the lagoon sites to develop a decision framework to choose strategies, interventions and measures to manage the existing and future problems in the lagoon. This is accomplished using an integrated planning approach, considering ecosystem services to assess the social, economic and ecological state of the lagoon and linking this to spatial planning methodology. The final products of ARCH are roadmaps for implementation of realistic solutions at the lagoon scale, a management guide for coastal managers and policy makers in Europe and the European Lagoon Management Handbook. The project will actively disseminate products and experiences via newsletters, multiplier seminars, a website and specific web-tool for discussion, and a final conference. The legacy beyond the lifetime of the project is ensured by the connection to international networks, like the UNESCO HELP-program.