Although there is strong evidence for the effect of interparental conflict on adolescents' internalizing and externalizing problems, little is known about the effect on the quality of adolescents' relationships. The current study investigates the link between adolescents' friendships and interparental conflict as reported by both parents and adolescents. It considers early adolescents' emotion regulation ability and attachment security as mediators. The analysis is based on a longitudinal study with two waves separated by 12 months. The participants were 180 two-parent families and their adolescent children (50.5% girls), the average age of the latter being 10.61 years (SD = 0.41) at the outset (Time 1). Binomial logistic regression analysis revealed that perceived interparental conflict increased the risk of instability in friendship relationships across the 1-year period. Structural equation modeling analysis indicated that the association between perceived interparental conflict and friendship quality was mediated by emotion regulation and attachment security. The discussion focuses on mechanisms whereby interparental conflict influences early adolescents' friendship relationships.