The project "Impactos-CC: Understanding and Enhancing the Impacts of Citizen Science in Spain" has pioneered the collaborative development of a tool to measure the impacts of citizen science at the national level. This tool is mainly based on the work of nearly a hundred scientists in Spain, as well as previous work carried out by other European researchers. This Final Report presents the methodology for the co-design of citizen science impact indicators and the results of their application to twenty-nine projects carried out in Spain. The Impactos-CC project has been coordinated by the Ibercivis Foundation, in collaboration with the Spanish Foundation for Science and Technology (FECYT) - Ministry of Science, Innovation and Universities.