While disagreeing over the reasons why the performance of civic obligations seems to be declining, conservatives and liberals agree that people need to be reminded of their duties as citizens for this decline to be halted. But do these exhortations work? This paper tests two theories about how people become volunteers. The "normativist" perspective assumes that volunteer behavior flows from socialization into pro-social attitudes; the "social practice" perspective stresses the formative role of practical experiences and social participation. Using a panel study of high school seniors who were reinterviewed in their mid-20s and again in their early 30s, we show that volunteer work undertaken in high school has long-term benefits as does social participation more generally but that socialization into pro-social attitudes has an even stronger influence on volunteering in middle age. The implications of our study are that mandatory community service programs can boost later volunteer efforts but that socialization into appropriate citizenship attitudes is of equal, if not greater, importance.