Past research has shown that, while psychological control increases the risk for adolescents' antisocial behavior, maternal knowledge of adolescents' activities decreases this risk. Yet, research is somewhat inconclusive about the role of psychologically controlling parenting in parental knowledge. Also, the role of both predictors in prosocial behavior remains largely unknown. In this 1-year, multi-informant, prospective study, we investigated these issues by recruiting a sample of Turkish early adolescents (N = 229, M[subscript age] = 11.89 years, SD = 0.32, 47.0% boys) and their mothers. After controlling for baseline adolescent-reported maternal knowledge, we found mother-reported psychological control to negatively predict adolescent-reported maternal knowledge 1 year later. In turn, maternal knowledge related negatively to antisocial behavior and positively to altruistic prosocial behavior (but not to instrumental prosocial behavior). These findings highlight the key role that maternal psychological control and knowledge can have in adolescents' social functioning.