Internalizations have intrapsychic as well as interpersonal aspects. Both are closely interrelated but, to some extent, can be evaluated independently. Intrapsychic and interpersonal aspects must be considered when we want to determine whether internalizations primarily serve the subject's defensive or growth needs. The present paper, in taking up this question, focuses especially on three interpersonal dimensions called exclusivity of dependence, interpersonal intensity, and status of boundaries. It then introduces the concept of transactional modes—comprising 'binding', 'expelling' and 'delegating'—in order to further illuminate how these interpersonal dimensions, while occurring in various combinations, can affect differently any evolving internalizations. Particularly the vicissitudes of adolescent separation bring into view how internalizations, in various ways, may serve the needs of defence, of growth, or both.