Mountains cover 30% of the land area and are home to 17% of the EU´s population, meaning that every 6th EU citizen lives in mountainous areas. While we often associate mountains with breathtaking landscapes that offer perfect sites for relaxation, in truth, mountains are much more than that. In fact, mountains play a crucial role in our daily lives by providing vital resources and key community systems to the global population. Mountains like other areas face unprecedented challenges in terms of climate change (CC), however mountain ecosystems are more sensitive to CC. The harmful conditions provoked by CC are exacerbated by the significant deficits in adaptation responses mountainous areas have, stemming from several existing gaps, including shortcomings in CCA options, deficits in the uptake and the lack of coherence. MountResilience has been formulated to increase the adaptation capacity of mountainous regions and communities so as to strengthen climate resilience within the European mountainous biogeographical region (Alpine biogeographical region). The project aims to accelerate the climate resilient transformation of 10 of the most relevant communities and regions located in the mountains in 9 European countries. 6 of the regions will develop and test transformative CCA solutions (technological and social innovations with nature-based solutions at their core). These solutions will address policy, governance, societal needs and behaviours, technological requirements, public and financing targets, and CC risks typical of mountainous areas. Regional quadruple-helix partnerships will use open innovation, participatory decision-making, stakeholder engagement approaches, and effective communication to mobilise, engage, and reach out to key communities. The remaining 4 regions will serve as "replicator" regions, repurposing CCA solutions and lessons learned from the demo regions in their regions through special initiatives to improve their adaptive capacity.