The concept of borderline states raises questions about nosology, psychopathology and treatment. This borderline-concept will be approached, on one hand, with regard to the baby/teen problematic, and, on the other hand, from the perspective of institutional structures. The author stresses the importance of a two-way reading of the theory of deferred action, then recalls some principles of the baby/teen problematic. Lastly, the example of Therapeutic, Educative and Pedagogical Institutions (ITEP) is presented as a way of thinking about mediating structures.

Adolescence, 2021, 39, 2, 327-338.