Research indicates that political interest is one of the most important individual-level predictors of news media use, public opinion formation and engagement. When, how and why some citizens develop a strong interest in politics, while others do not, is however less clear. The present study analyses the development of political interest during the formative years of adolescence, using a five-wave panel study of adolescents, their parents and friends conducted in Sweden. More specifically, based on the citizen communication mediation model, we analyze how news media norms and habits among family and friends influence the development of political interest among adolescents during a period of five years. Taken together, the findings lend support for several of the hypotheses derived from the communication mediation model. But while empirical support for distinct mechanisms and processes are found, news norms among parents and peers seem to be relatively weakly related to adolescents’ political interest.