Severe destructive behavior against themselves and others by adolescents with boundary disorders often occurs during their development as a form of coping with traumatic stress. These and other non-verbal "acted-out messages" are described as forms of communication typical of adolescents who, as a consequence of trauma, are unable to express themselves using language. Such behavior determines the everyday life and the therapy of these adolescents. Their impaired information perception and processing causes--among other problems--deficits in memory functions, poor self-regulation, sensory modalities and language abilities, and primary responses such as flight/fight and freezing reactions, all of which contribute towards arrested development. The treatment of complexly traumatized adolescents poses special challenges in arranging and organizing in-patient psychotherapy. Different therapeutic steps are described, such as first recognizing and overcoming traumatizing reenactments, second, developing and providing safe places, third, building up and extending competencies, and fourth, developing playing and symbolizing abilities. These steps are necessary for coping with traumatizing experiences.