Social marginalisation and exclusion significantly affect young European citizens’ well-being and social welfare; it also contributes to constraining civic participation, increasing the problem of ‘disenfranchisement’, where youths find themselves unable to change their social conditions and, thus, withdraw from civic and political engagement. This can create a lack of citizenship and trust in governance and social belonging. The challenges of social exclusion accentuate the importance of finding mechanisms that can improve young peoples’ situations and shape more cohesive societies across the EU. This need has also been recognised as a priority in current and future policy in the EU, for example, in the EU Youth Strategy. Citizen science (CS) – broadly defined as ‘voluntary participation of the public in the scientific process’ and currently launched by the European Commission (EC) as an open science priority – holds great potential for contributing to new knowledge and innovations, helping create more inclusive societies for young people by supporting science–society collaboration and the active engagement of citizens in research and innovation. Yet CS is less developed in the social sciences, and evidence of the actual outcomes of CS in social science research is still scant. Thus, YouCount will respond to these scientific and societal needs by developing youth citizen science in the social sciences (Y-CSS) together with youths as citizen scientists (YCS), supporting the implementation of hands-on CSS in practice and providing a solid evaluation base of the implementation and outcomes of CSS.