This deliverable describes the ACTION impact assessment methodology, the co-design process followed for its development and how it will be applied to CS projects and to ACTION overall. The ACTION impact assessment methodology considers scientific, social, economic and political impacts; it links CS impacts to EU Sustainable Development Goals (SDGs) and considers also the potential contributions to MORRI indicators. Its aim is to support the ACTION consortium, but also CS managers and researchers working on the benefits of CS, by providing a multi-dimensional, flexible and adaptable framework to be used in their work. This framework is under usage at the time of writing as an internal tool for assessing ACTION’s pilots and will be regularly improved and updated in the next months of the project by taking on board feedback coming from its application. It is complementary with D6.2 which offers data gathering instruments to be used in the actual application of the methodology here described (accessible here: https://zenodo.org/record/3968460#.XyQRCB1S-u5 DOI 10.5281/zenodo.3968459). .