This study examined temperament development from early to middle adolescence and the roles of parenting styles and parent temperament in this development. The sample consisted of 842 adolescents (n = 842 in Grade 6; 54% girls) and their parents (N = 707). Adolescents assessed their temperament in Grades 6 and 9 and parents assessed their temperament and parenting styles when adolescents were in Grade 6. The results showed that adolescent affiliativeness increased and effortful control decreased from early to middle adolescence. High parental warmth was related to higher adolescent affiliativeness and higher effortful control, but also to a decrease in adolescent negative affectivity. High parental behavioral control, in turn, was related to adolescents' initially higher, but subsequently decreasing surgency. Further, high parental psychological control was related to lower adolescent effortful control. Parent temperament was also related to adolescent temperament, and parenting styles partially mediated several associations between parents' and adolescents' temperament. The results suggest that parents' temperament and parenting styles are related to adolescents' temperament development in a complex manner, even as adolescents seek to gain independence from parents. Understanding the roles of parental temperament and parenting in adolescent temperament development is important in order to support adolescents in their development towards a stable adulthood.