Adolescents often experience heightened socioemotional sensitivity warranting their use of regulatory strategies. Yet, little is known about how key socializing agents help regulate teens’ negative emotions in daily life and implications for long-term adjustment. We examined adolescent girls’ interpersonal emotion regulation (IER) with parents and peers in response to negative social interactions, defined as parent and peer involvement in the teen’s enactment of emotion regulation strategies. We also tested associations between rates of daily parental and peer IER and depressive symptoms, concurrently and one year later. Adolescent girls (N = 112; Mage = 12.39) at temperamental risk for depressive disorders completed a 16-day ecological momentary assessment protocol measuring reactivity to negative social interactions, parental and peer IER, and current negative affect. Results indicated that adolescents used more adaptive strategies with peers and more maladaptive strategies with parents in daily life. Both parental and peer IER down-regulated negative affect, reflected by girls’ decreased likelihood of experiencing continued negative affect. Higher proportions of parental adaptive IER predicted reduced depressive symptoms one year later. Findings suggest that both parents and peers effectively help adolescent girls down-regulate everyday negative emotions; however, parents may offer more enduring benefits for long-term adjustment.