Mentalization-based therapy (MBT) is an evidence-based treatment for patients with borderline personality disorders. For therapeutic work with adolescents, MBT has been adapted and already shows promising evidence of effectiveness in treating self-harming youth with a borderline diagnosis. This compact overview presents the core model of MBT-A for the first time in the German-speaking world. The authors first explain the theory of mentalization and then apply it to the specific conditions of adolescence. The practical section introduces mentalization diagnostics as well as the attitudes and interventions of MBT-A. This approach differs from adult therapy through a more active stance and the integration of a family therapy component.