Together with the Netherlands? Institute for Sport and Physical Activity (NISB) and 15 National Sport Organizations (NSOs), representing 3.2 million sport club members, we propose a research study to examine changes in membership and engagement in sport clubs. Combining a sociological, geographical and public administration perspective, we will analyze to what extent people bond themselves to one another in sport clubs and are willing to engage themselves with their club. We will zoom in on regional and social differences and variations with respect to each branch of sport. The study will be based on a mixed methods design, including both quantitative and qualitative research and the application and assessment of interventions. The goal of the research project is to develop new insights into (changing) meanings of citizenship, membership and membership organizations in Dutch society in general and sport organizations in particular. In doing so, we intend to help Dutch sport organizations to successfully anticipate and respond to changing meanings that sport participants attach to club membership and engagement, and to contribute to wider scholarly and public debates on civil society and social cohesion.