Because a young child is a rapidly growing organism, physical defects may impede progress and development to a great extent. It is important, therefore, to recognize abnormalities early so that corrective measures may be applied as soon as possible. The child's physical and mental growth can be determined by an evaluation of his height, weight, mental test scores and personality ratings. However, all such determinations are of much more value when they can be compared with a reliable norm. In this small book, standards on twenty-one traits in nursery school children of the Merrill-Palmer school are presented. In order to overcome the usual difficulties that arise in coordinating physical, mental and social and environmental measures, the percental method of statistical summary is employed. In addition to the usual physical measurements and mental tests, percental ranks are given for personality ratings, activity ratings, caloric intake, protein, fats and carbohydrate intake, and