Despite the fact that numerous political parties in Western democracies include separate youth chapters, these have not been studied systematically in political research. There are two reasons to study youth chapters: we know youth participation has strong and enduring political socialisation effects, while several authors have expressed concern about a decline of political engagement among adolescents. Our assumption is that youth chapters fulfil two functions within a party: recruitment of members and ideological innovation. Given the structural evolution toward cartel parties (Katz & Mair), both functions have become partly obsolete. Youth chapters of Flemish political parties have indeed lost 70 percent of their members since the 1970s. A survey among city councillors confirms the recruitment,function of,youth chapters: 41 percent of them started their political career in youth chapters. The demise of youth chapters therefore can be seen as a clear indication of a structural transformation of political parties.