The report summarizes the presentations, discussions, and conclusions of the Citizen Science and Smart Cities Summit organised by the European Commission Joint Research Centre on 5-7th February 2014. In the context of the Summit, the label Citizen Science was used to include both citizen science projects, and others that are about user-generated content, not necessarily addressing a scientific process or issues. The evidence presented by 27 different projects shows the vitality and diversity of the field but also a number of critical points: ? Citizen science project are more than collecting data: they are about raising awareness, building capacity, and strengthening communities. ? Likewise, smart cities are not only about ICT, energy and transport infrastructures: Smart cities are about smart citizens, who participate in their city?s daily governance, are concerned about increasing the quality of life of their fellow-citizens, and about protecting their environment. Technology may facilitate, but is no solution per se. ? Unfortunately to date there seems to be little synergy between citizen science and smart cities initiatives, and there is little interoperability and reusability of the data, apps, and services developed in each project. ? It is difficult to compare the results among citizen science, and smart cities projects or translate from one context to another. ? The ephemeral nature of much of the data, which disappear short after the end of the projects, means lack of reproducibility of results and longitudinal analysis of time series challenging, if not impossible. ? There are also new challenges with respect to the analytical methods needed to integrate quantitative and qualitative data from heterogeneous sources that need further research. ? Building and maintaining trust are key points of any citizen science or smart city project. There is a need to work with the community and not just for, or on, the community. It is critical not just to take (data, information, knowledge) but to give back something that is valued by the community itself. The development of citizen science associations in Europe and the US are important developments that may address some of the points above. There are also actions through which the European Commission Joint Research Centre can make an important contribution: ? Map citizen science and smart cities projects, and generate a semantic network of concepts between the projects to facilitate search of related activities, and community building. ? Provide a repository for citizen science and smart cities data (anonymised and aggregated), software, services, and applications so that they are maintained beyond the life of the projects they originate from, and made shareable and reusable. ? Develop regional test beds for the analysis and integration of social and environmental data from heterogeneous sources, with a focus on quality of life and well-being. ? Undertake comparative studies, and analyse issues related to scaling up to the European dimension. ? Support citizen science and smart cities projects with the JRC knowledge on semantic interoperability, data models, and interoperability arrangements. ? Partner with the European Citizen Science Association, and contribute to its interoperability activities. ? Work towards making the JRC, and the European Commission, a champion of citizen participation in European science.