Two longitudinal studies examined associations between relational aggression and friendship quality during adolescence. In Study 1, 62 adolescents in Grades 6 (25.8%), 7 (32.3%), and 8 (41.9%) completed assessments of friendship affiliations, relational and overt aggression, and friendship quality at 2 time points, 1 year apart. Results using actor partner interdependence modeling indicated that high levels of relational aggression predicted increases in self-reported positive friendship quality 1 year later. In Study 2, 56 adolescents in Grades 9 (66.7%) and 10 (33.3%) attended a laboratory session with a friend in which their conversations were videotaped and coded for relationally aggressive talk. Target adolescents completed measures of positive and negative friendship quality during the laboratory session and during a follow-up phone call 6 months later. Analyses revealed that high levels of relationally aggressive talk at Time 1 predicted increases in negative friendship quality 6 months later. In addition, among adolescents involved in a reciprocal best friendship, high levels of observed relationally aggressive talk predicted increases in positive friendship quality over time. Taken together, these studies provide support for the idea that relational aggression may be associated with adaptive as well as maladaptive outcomes within the dyadic context of adolescent friendship. (Contains 6 tables and 2 footnotes.)