The authors sought to identify diagnostic criteria that are relatively specific to borderline personality disorder in severely ill adolescent inpatients and that may predict a stable borderline personality disorder during this turbulent time. Twenty-one adolescent inpatients with borderline personality disorder were contacted 2 years after the index hospitalization (baseline). Seven of these patients met criteria for borderline personality disorder at follow-up. The ability of baseline criteria for borderline personality to predict the diagnosis of borderline personality disorder at follow-up was determined. Criteria for borderline personality disorder were sensitive for the stable disorder but not very specific. Without follow-up data, the diagnostic significance of symptoms of borderline personality disorder in adolescents appears uncertain.