In the United States, a psychometric psychology dominates the thinking of educators. For traditional, political, and social reasons, developmental psychology rarely informs educational practices. This is the case even though studies show that the inducing of cognitive learning before a child is ready will reduce the child's learning potential and may result in the child's being erroneously diagnosed as handicapped. A substantial body of research suggests that children should not begin formal academic instruction until 7, 8, or even 11 years of age. However, chronological age is not always a reliable index of school readiness. Recent findings support the importance of maturity as a key predictor of school readiness. In a national study, 300 children who entered school 2-5 years later than the required entrance age of 6 years had no difficulty completing elementary school at the same age as those who entered earlier. Expert opinion recognizes that forced learning can cause frustration, anxiety, alienation, and loss of interest in learning. Whatever gains may result from psychometrically determined educational practices are outweighed by harm done to children's self-concept, health, and emotional and intellectual development. The psychometric, traditional approach must be replaced with a developmental approach that examines the needs of the child and the process of the child's development. (RH)