Results indicated that experiencing peer pressure from both teens’ best friends and their larger peer groups during early adolescence predicted teens' later involvement in romantic relationships characterized by relational aggression and victimization. Analysis revealed that adolescents observed to have a best friend who used pressuring strategies intended to undermine their autonomy were more likely to perpetrate relational aggression in romantic relationships and have a romantic partner who reported feeling victimized by relational aggression 3 years later. Moreover, peer pressure from teens' larger peer group also predicted increases in levels of adolescents' relational aggression. Difficulties establishing autonomy in early adolescence within the family contexts have previously been linked to numerous deleterious developmental outcomes, including increased levels of peer rated hostility in young adulthood. It may be that teens who experience consistent attempts by their friends, whether closer and more distant, to undermine their autonomy may become increasingly frustrated by this behavior over time and eventually act on their frustrations in different contexts and in different forms, such as by being relationally aggressive toward their romantic partners. Behaviors which undermine autonomy are also similar enough to those characterizing relational aggression that it is likely that teens, unwittingly or not, may learn the advantages of the behaviors employed by their autonomy-undermining, pressuring friends to produce a desired outcome and use them in their own relationships. Data were drawn from a larger longitudinal investigation of adolescent social development in familial and pure contexts. Participants included 97 teenagers along with their best friends and the romantic partners, assessed over a 3-year period. Tables, references