Borderline personality disorder is characterized by a consistent pattern of intense, unstable, and unpredictable interpersonal relationships, thought contents and processes, affects, and self-perceptions. Many children who manifest borderline personality disorder have a history of severe physical or sexual abuse and have been raised in very dysfunctional families. Borderline personality disorder is diagnosed when the pattern of behaviors is severe and characterizes an individual's personality, meaning that it involves a consistent pattern of functioning that is maladaptive for the individual in relationship to his/her environment. Children with this disorder learn that relationships are typically painful and threatening; however, they have received enough positive attention and affection to desire the beneficial aspects of relationships; consequently, children with borderline personality disorder pursue relationships because of their benefits but are leery of relationships because of their painful nature, thus preventing emotional intimacy and fostering the tendency toward pre-emptive rejection. This article also discusses comorbidity and differential diagnosis; obstacles to recognizing borderline disorders in children; behaviors associated with borderline problems in children (problematic interpersonal relationships, impulsiveness, intense and unstable affect, lack of age-appropriate consistent sense of self, and self-destructive behavior); and individual therapeutic interventions. Suggestions for interventions with children who have the disorder or its characteristics come primarily from psychodynamic and cognitive-behavioral theories, although some recent work on pharmacological treatment has also occurred. Psychotherapy primarily involves reducing anxiety, promoting ego development, and helping the child develop healthy interpersonal relationships. A case study is included. 2 notes and 26 references