OBJECTIVE: The purpose of this study was to determine whether rates of psychopathology differed between the families of a group of children and adolescents with borderline personality disorder and the families of a psychiatric comparison group. METHOD: The rates of psychiatric disorders in the families of 44 child and adolescent outpatients with borderline personality disorder were compared with the rates in the families of a psychiatric comparison group of 100 children and adolescents, none of whom had a diagnosis of borderline personality disorder. Psychopathology in family members was ascertained by the family history method with the use of information from semistructured interviews with the subjects in the two study groups and with their parents or guardians. The adults were systematically interviewed regarding specific DSM-III-R disorders in their families. RESULTS: The families of the patients with borderline personality disorder had significantly greater rates of psychopathology, particularly in the areas of depressive, substance abuse, and antisocial disorders. CONCLUSIONS: The finding of higher rates of psychopathology among the family members of the group with borderline personality disorder supports the hypothesis that a history of significant family psychopathology is associated with the disorder.