This study was designed to test for specificity in the relationship between individual friendship provisions and adjustment across early adolescence. Using a narrative procedure, attachment (i.e., accessing care) and affiliation (i.e., forming cooperative partnerships) were found to be distinct functional themes organizing 293 adolescents’ (Mage = 13) internal representations of their best friendship across three annual measurement occasions. Longitudinal, cross‐lag analyses revealed a unique transactional relationship between friendship affiliation and greater social competence over time, controlling for friendship stability, maternal relationship quality, socioeconomic status, and gender. By contrast, friendship attachment predicted fewer subsequent internalizing symptoms from ages 14 to 15. Together, findings point to the importance of understanding individual differences in the content of adolescents’ internal representations of friendship.