Current scientific research and recent policy initiatives reveal an intense interest in the effect of social capital on a broad range of socioeconomic outcomes both at the individual level (e.g., civic attitudes) and the societal level (e.g., democratic or economic performance). Despite persistent argumentation in this debate that voluntary associations are of crucial importance in this process, empirical research usually reveals but a weak relation between membership and democratic (or civic) attitudes. In this paper, we follow recent arguments that various types of associations may play different roles. Specifically, we empirically distinguish between bridging and bonding associations based on the socioeconomic diversity within an association. Using a dataset on association membership in Flanders, we find empirical support for the view that individuals’ values and attitudes indeed differ across members in (predominantly) bridging or bonding associations.