Why do some young citizens vote, why do others protest? Political socialization and political attitudes play an important role in shaping young citizens' political participation. Changing political attitudes have been held responsible for the change in the political repertoire of young citizens. Lower trust and political efficacy have lead young citizens to increasingly use unconventional instead of conventional forms of political participation. Differences between countries in political attitudes and political repertoire, however, call for a micro-macro approach. Based on the political opportunity theory, the minority politics literature, and the electoral competition theory, I argue that the political system's openness in terms of descriptive and substantive representation fosters young citizens' conventional over unconventional participation. I test these hypotheses by multilevel analysis and rely on six European Social Survey waves (2002-2012) and an original dataset descriptive (candidates' and representatives' age) and substantive (saliency and politicization of issues specific to young citizens).
