Abstract:After reviewing the history of conceptual and procedural changes in borderline patients, the author pointed out that the recent emphasis on the aggression and its origination in infancy in its treatment seems to blur the developmental issues in pre‐adolescence and adolescence and to present difficulty in concluding the treatment. And a borderline case of the patient, a 20–year‐old single woman with various symptoms, was presented. An examination of the course of treatment revealed that in order to better understand the process of therapeutic change it would be best to set the third phase with a strong narcissistic coloration between the working‐through and separateiontermination phases described by Masterson, J.F. Finally, it was emphasized that this narcissistic phase is a repetition not only found in childhood, but also in the preadolescent development and its distu