This study builds on the well-known civic voluntarism model of political participation. By doing this, we contribute to a political sociology of participation by refining the role of socialization in political engagement. We suggest that the action repertoires of young people engaging in politics can be narrower or broader owing to their previous embeddedness in certain social settings, which act as spheres of socializing practices. We focus more specifically on three socializing spheres: educational (schools), recreational (social clubs), and civic (community organizations). Our analysis, covering nine European countries, largely confirms our expectations. We find that active engagement in these spheres of socializing practices leads to a broader range of political activities in young people's action repertoires. This holds in particular for the civic sphere. The findings provide a fresh look at the role played by socializing spheres, shifting the focus from the dichotomy between participation versus non-participation to an analysis of the breadth of participation.