BEGIN proposes an approach to climate resilience for cities that mimics nature’s potential to deal with flooding. Blue and Green Infrastructure (BGI) supports existing grey infrastructure to cope with extreme weather events (reducing flood risk by 30%) and improves urban liveability. Research (TEEB, 2015) shows that BGI benefits outweigh costs by a factor of 2 to 10. However, widespread implementation is hampered by financial & governance complexities. BEGIN helps cities overcome BGI´s implementation barriers through Social Innovation (SI) that empowers multiple stakeholders to contribute (in kind, funds) to the design, construction and maintenance of BGIs. SI requires a new way of working for cities and valuation of multiple benefits together with communities. Transnational collaboration is needed because cities are missing the opportunities to incorporate BGI in urban investment projects due to a lack of local technical and social innovation capacities. From the start, BEGIN is a unique transnational city-to-city exchange programme with transnational expert teams that facilitate joint implementation of BGI projects in 10 leading NSR cities.The pilots will demonstrate how BGI and SI can generate effective climate change adaptation solutions that are financially feasible and can be incorporated in urban planning approaches. The pilots provide an evidence base and a toolbox to propel uptake in NSR. Lessons will be shared within larger city networks UNISDR, ICLEI, Mayors Adapt.