The author traces some of the literature related to such concepts as the development of the therapeutic alliance and collaboration in the inpatient and residential psychiatric treatment of disturbed adolescents. The more recently developed concept of "mentalization" is discussed, especially with its relevance to the psychotherapy of difficult-to-treat adolescent patients. A case presentation highlights the establishment of relatedness and trust with such a patient. The case is described in terms of the mental activities of both therapist and patient that facilitated the psychotherapy process in a number of ways. Mentalization is seen as a useful concept, both in terms of understanding the process of psychotherapy, and as a fundamental attribute of the mental activities of the therapist and, likewise, fostered in the patient.