The basic task of adolescence is the process of separation-individuation described by Margaret Mahler, as a result of which identity is formed. And it is not possible to speak of identity in isolation from the body. Both body image, the body Self, as well as the experience of movement are of great importance. The available classifications of disorders do not take into account the adolescent’s way of experiencing the body. In our opinion, the inclusion of the body in the diagnosis preceding psychotherapy can provide a lot of information about the inner experiences of young persons, their relationship to themselves, and their relationship styles. Inspired by Vittorio Lingiardi and Nancy McWilliams’ assessment of mental functioning of adolescents (M-axis) as part of the PDM-2 (Psychodynamic Diagnostic Manual. Second Edition) classification of mental disorders, we propose an extension of the axis to include the ability to build a coherent identity at the sensory, mental and emotional levels within the structures of the body. We present the original Body Experience Scale. Short clinical examples from work in psychotherapy with adolescents illustrate the presented proposal. The theoretical point of reference is psychodynamic theory and the theories connecting body and mind.