Fifty-two children were observed in a community nursery school over a three year period. The children ranged from four to six years of age, and attempts were made to rule out obvious pathology in a 'normal' middle class population sample. By the fourth year of the study, only four children out of forty-five were felt to have maintained progression in their development. The others, it was found, had some degree of significant pathology. The authors speculate about the possible explanations for this astonishing data, and suggest that we may need to review our developmental model for the first six years of life. They advise caution, however, in making revisions.