While much thought has been given to problems of interpretation in the treatment of adult patients, they have, as yet, not been studied with all their implications, where children are concerned. One aspect of importance is related to the changes taking place in the child's developing ego, the part of the personality to which interpretations are conveyed. It is clear that in the course of development questions relating for instance to the growing capacity to tolerate frustration or to master anxiety must affect the choice, formulations, and timing of interpretations. It must be kept in mind that in many cases which are referred for treatment, different aspects of the ego are not on a level corresponding to the child's age. Attention is drawn to the need to remain aware of this in order to find the optimal conditions for transmission and assimilation of interpretations into the personality of child patients.