This study examined adolescents' ability to utilize emotional repair—to actively change negative moods to more positive moods—as a predictor of the quality of their developing peer and romantic relationships over time. Utilizing observational data and partners' reports, adolescents (N = 184), their close peers, and their romantic partners were followed from ages 15–19. Adolescents with initially stronger emotional repair abilities were rated as increasingly socially competent over time, and both displayed and experienced increasingly positive interactive behaviors with close peers over time. These adolescents' romantic partners also reported more positive relationships, with enhanced communication, and fewer critical, blaming, or hostile interactions. Implications for the role of emotional repair abilities in the development of successful relationships during adolescence are discussed.