Interpersonal approaches based on the classic concepts of psychoanalysis draw their significance not only from guiding therapists but also provide instruments for empirical psychotherapy research, particularly focussing on the therapeutic process itself. The Dusseldorf Short Term Psychotherapy Project uses several strategies of the SASB-CMP method to examine the interrelation among certain groups of disorders, different courses of treatment, and outcome in dynamic short term psychotherapy. In addition, this paper uses the concept of CMP-based therapeutic interventions to analyze focus-adherence and offers a system for the classification of other, not focus-related therapeutic interventions. For understanding the effects of dynamic short term psychotherapy, it is essential to consider the distinction between more specific approaches, e. g. interpretation, transference, and insight on the one hand, and more general concepts, e. g. emotional experience, absence of re-traumatization, direct or indirect support on the other hand. The 'principle of interpretation' needs a relatively structured patient's ego, while in other cases the basic (re-)organizing of the patient has to be the crucial goal of therapy. This leads to the assumption that successful outcome is achieved by different ways depending on the patients' differing structural levels. The 2 pilot cases of this study illustrate that based on a higher level of structural functioning, more CMP-specific interpretations in the here and now are used to obtain good results, whereas in a case of lower level the first aim is to strengthen the patient's ego functions and to scrutinize his CMP in the there and then.