It is demonstrated that Nature Based Solutions (NBS) efficiently and effectively contribute to climate adaptation. However NBS need to be adapted locally and to be coherently chosen in order to assure sustainability and “no side effects”. To achieve this, ARCADIA will mobilise 8 European regions and communities – from Italy, Croatia, Austria, Denmark, Sweden, Bulgaria, Romania, Slovenia - to accelerate NBS adoption and assist them in accessing up-to-date, evidence-based actionable knowledge, guidance, knowledge-intense tools and services, mutual learning and networking opportunities. The project will foster enabling conditions to accelerate regeneration using NBS, by analysing individual and socially determined perceptions of risks and solutions, and experimentally designing incentives and behavioural nudges fostering social acceptance and community actions. In ARCADIA, the definition of regional ambitions and of methodologies and approaches co-developed at consortium level, will be followed by the implementation of 15 co-innovation labs with the engagement of the interested communities and societal partners; the learning across policy areas will be exploited to up-scale and deploy at large scale the solutions in the regions, developing robust policy and economic tools (regulations, funding schemes, business models, investment tools). Strategic objectives of the proposal are: 1. Co-design regional strategies to accelerate transformative adaptation, building upon and mainstreaming innovative, actionable NBS with demonstrated feasibility, effectiveness and social value 2. Assist and empower communities, public administrations and businesses 3. Stimulate collaborative knowledge building and transfer, developing capacities and capabilities 4. Promote coherence and exploit synergies, value and production chains, and public and private spheres of business innovation 5. Advance EU research & innovation agenda on NBS and EU Mission Adaptation.