The relation of attachment security to multiple domains of psychosocial functioning was examined in a community sample of 167 early adolescents. Security of attachment organization, assessed using the Adult Attachment Interview, was linked to success in establishing autonomy while maintaining a sense of relatedness both with fathers and with peers, even after accounting for predictions from qualities of the mother-teen relationship. Growth curve analyses revealed links of insecurity to increasing patterns of externalizing behavior and higher and stable patterns of depressive symptoms across adolescence. Implications for a developing theory of the connections of the attachment system to multiple domains of functioning in adolescence are discussed.