During the last years, empirically based knowledge concerning psychopathology, etiopathogenesis and treatment of borderline personality disorder (BPD) has significantly improved. Today, most researchers postulate a pervasive affective dysregulation at the core of borderline symptomatology. Affective dysregulation in BPD is seen as a consequence of an interplay between genetic vulnerability, sociobiographic experience and dysfunctional behaviour. Disorder-specific psychotherapeutic treatments, especially the dialectical behaviour therapy (DBT) developed by Linehan reach significant treatment effects under both outpatient and inpatient conditions. In addition, recent studies on psychopharmacological treatment with promising results have been published. Most recently, DBT has been expanded to treat severe BPD comorbidity like substance abuse and post-traumatic stress disorder (PTSD).