Variability in adolescent-friend similarity is documented in a diverse sample of African American, Asian American, and European American adolescents. Similarity was greatest for substance use, modest for academic orientations, and low for ethnic identity. Compared with Asian American and European American adolescents, African American adolescents chose friends who were less similar with respect to academic orientation or substance use but more similar with respect to ethnic identity. For all three ethnic groups, personal endorsement of the dimension in question and selection of cross-ethnic-group friends heightened similarity. Similarity was a relative rather than an absolute selection criterion: Adolescents did not choose friends with identical orientations. These findings call for a comprehensive theory of friendship selection sensitive to diversity in adolescents' experiences. Implications for peer influence and self-development are discussed.