This study examined the association between youths' triangulation in marital conflict and three aspects of their peer relations in 416 families during early adolescence. A 4-wave, longitudinal research design was used. As hypothesized, triangulation was associated negatively with perceived support from friends and positively with perceived peer rejection. Triangulation was a risk factor for both sons and daughters. Adolescent problem behavior did not mediate the significant association between triangulation and perceived friendship support. Adolescent problem behavior, particularly internalizing problems, completely me diated the association between triangulation and adolescents' perceptions of peer rejection, suggesting the important developmental role of adolescents' anxiety, depressive affect, and withdrawal. The implications of these findings are discussed in terms of Bowen's multigenerational family systems theory and social learning principles.