Children who were maltreated and enter foster care are at risk for maladjustment and relationship disturbances with foster carers. A popular hypothesis is that prior attachment relationships with abusive birth parents are internalized and carried forward to impair the child’s subsequent attachment relationships. However, the empirical base for this model is limited, especially in adolescence. We examined the attachment patterns of 62 adolescents with their birth parents and their foster parents; we compared them to a comparison sample of 50 adolescents in normal-risk families. Attachment was assessed using the Child Attachment Interview; adolescent-parent interaction quality was assessed from direct observation; disruptive behavior symptoms were assessed from multiple informants. Whereas nearly all of the adolescents in foster families exhibited insecure attachments to their birth mothers (90%) and birth fathers (100%), nearly one-half were classified as having a secure attachment with their foster mother (46%) and father (49%); rates of secure attachment toward foster parents did not differ significantly from the rate in comparison families. Within the foster care sample, attachment security to the foster mother was predicted from current observed relationship quality and the duration of current placement. In addition, attachment quality in foster adolescents was associated with fewer disruptive behavior symptoms, and this association was equally strong in foster and comparison families. Our findings demonstrate that there is substantial potential for maltreated children to change and develop subsequent secure attachments in adolescence.