CS Track, a research project funded by the European Commission, aims at broadening knowledge about citizen science by applying data analysis to publicly available information from the web and collecting complementary data through questionnaires and interviews with people who take part in CS activities. For this purpose, CS Track has collected publicly available data on more than 4500 projects from websites and online platforms and conducted a survey with more than 1000 participants from 30 European countries. Taking this approach, CS Track generated insights about citizen science and its impact in various areas during the past three years. “Citizen science offers great potential for science and society, but this potential can only be fully realized if certain conditions are met. These conditions for success include, among others, strategies to ensure the active and long-term cooperation of citizen scientists. The aim must be to create an environment that motivates participants to get involved in the respective project - for example through educational offers, regular communication between volunteers and professional scientists in both directions, events, awards, certification and so forth. This aspect in particular is often very time-consuming and cost-intensive for the project initiators, but can be the deciding factor as to whether a project succeeds or fails.” Dr Raul Drachman, CS Track project coordinator. This brochure provides a summary of the research work carried out by the project team in the first 30 months of CS Track’s lifetime.