The authors give a practical introduction to the theoretical background of the instrument of the relationship axis of the Operationalized Psychodynamic Diagnostics in Children and Adolescents (OPD-KJ-2) and a clear guide to the rating. In addition, they describe for the first time significant conceptual extensions of the relationship axis. Using clinical case material, the possible uses for a wide range of questions in different clinical contexts are shown. Case studies from practice make it clear what enrichment the use of the OPD-KJ-2 axis 'relationship' offers for psychotherapeutic work.