From 1945 onward, patients have found their way to long-term ambulatory psychoanalytic treatment (psychoanalytic psychotherapy and psychoanalysis) in the government-funded Netherlands mental health care system. So far it is not entirely clear what differences exist between patients assigned to either psychoanalytic psychotherapy (PP) or psychoanalysis (PA). Both clinicians and researchers indicate a clear need for systematic empirical data on differential selectivity for patients assigned to psychoanalytic treatment (Gunderson and Gabbard 1999). In the Netherlands, a monitoring system was developed to register patients' mental health status before and during treatment in order to systematically gather empirical data of this sort.