This study examined how peer norms condition the effect of romantic involvement on adolescents' externalizing and internalizing problem behaviors. We hypothesized that, as a result of social control and social learning, adolescents who start a romantic relationship report more problem behavior when romantic involvement was not normative behavior in the peer group. We tested this hypothesis for two different peer groups: the friendship network and the class. Using large-scale panel data of Dutch adolescents (N = 2,302; M[subscript age] = 14.5) collected in 222 school classes that included sociometric measures, we found that adolescents who started dating reported more problem behavior if dating was not in line with the class' norm compared with when dating was in line with the class' norm. Friends' norms did not moderate the association between romantic involvement and problem behavior.