From the standpoint of mental health and perhaps even from the standpoint of human culture, the complete realization of the educational possibilities of the preschool child is of foundational significance. Normative and comparative studies performed at a psychological clinic at Yale examining norms of development in children from one month to five years of age show that there are irreducible individual differences in humanity that assert themselves even in early infancy. The traits and trends of the baby's personality are to a remarkable degree the product not of specific inheritance, but of conditioning environment. There can be no doubt that the first outlines, and to a certain extent the very texture of a personality, are laid down in infancy. A child's "personality makeup," so far as it is a describable subsisting reality, consists in the countless conditioned reflexes, associative memories, habits and attitudes which it acquires as a result of being reared by personal beings. All children are thus adapted to their parents and to each other. It is such considerations that give educational significance to the pre-school period of development. Mental hygiene, like charity, begins at home. But it does not end there. Nursery school and kindergarten alike will have an increasing part to play in developing specific forms of mental hygiene service, which will help to strengthen the home and make up for its deficiencies. This article delves into how both entities impact early development of a young child and concludes by highlighting the preservation of the parent-child relation. [Excerpts from this article are reprinted from "Childhood Education" v1 n1 1924 in celebration of "Childhood Education's" 125 year anniversary.]