The authors think, that psychological perturbations in women during the period immediately preceding and following childbirth brings about deepseated personality changes that will determine the future relationship between the mother and her child and all subsequent children. Hospitalization of the mother and child together is resorted to in three types of case: for the classic post-partum psychosis, for psychotic mothers showing serious personality troubles, and for early deviations in the mother-child relationship. For most children the alternative is being taken into care, or being placed in the hands of a series of mother-substitutes. Joint hospitalization allows a relationship to be established in a satisfactory environment, allows the mother-child relationship to be maintained, or a means of separation arranged if it should prove necessary. This practice opens new horizons in research into the psychology of mothers and the child's development in the earliest time of life. It should be possible to organize hospitalization of this type within the structure of the general hospital, and include it in the long-term treatment both of the mother and the child.