Authoritative parenting has been associated with positive outcomes for children and adolescents, but less is known about the mechanisms responsible for such effects. Two longitudinal studies examined the hypothesis that the relation between authoritative parenting and adolescents' adjustment is mediated by adolescents' level of dispositional optimism. In Study 1, university students' perceptions that their parents were authoritative predicted higher self-esteem, lower depression, and better university adjustment during the students' transition into, and throughout, university. Importantly, these relations were mediated by students' levels of optimism. In Study 2, high school students' perceptions that their parents were authoritative predicted higher self-esteem and lower depression six years later when they were young adults, and these relations again were mediated by students' level of dispositional optimism.