Mood swings, identity disorders and self-destructiveness are not uncommon expressions of impaired personality development in adolescence and can manifest themselves clinically as borderline syndrome. Although the onset of the disease is in childhood and often develops into a diagnosable disorder in adolescence, this clinical picture has so far mainly only been examined in adulthood. The scientifically sound contributions by well-known authors provide new insights into the epidemiology, diagnosis, etiology and therapy of borderline disorders in adolescence.