Abstract
Close college-age friendships provide differential opportunities for reinforcing dispositional tendencies and fostering accommodation or change. This finding was obtained from a cross-sectional study of 66 pairs of same-sex college-age friends (58% female). Each pair of friends was extreme and either very similar or different with regard to extraversion-introversion. Interviews with each friend were analyzed for references to each other's role in various friendship domains, including the setting of the friendship and position with regard to chatting, disclosing, expressing opinions about peers, and energizing the friendship. Matched friends mutually reinforced each other's similar dispositional tendencies. Friends with contrasting personalities showed patterns of personality accommodation as well as complementary reinforcement. Implications are discussed for embedding reciprocal theories of personality development in close friendships.