The Department of Child Hygiene of the Harvard School of Public Health established ten years ago the Center for Research in Child Health and Development. The Center was planned primarily to provide facilities for research upon well children living at home under normal conditions. These children, approximately three hundred in number, were enrolled at the Center, and of these, two hundred and twenty-five are still being studied from early in prenatal life through a major portion of their developmental period.3 The oldest children in the group are now ten years of age. A statistical analysis of the incidence of defective deciduous teeth among children enrolled in the study has been made by Miss Margaret F. Allen, Department of Vital Statistics, Harvard School of Public Health.4 Following this statistical analysis, a preliminary study of the nutrition of small groups of our children, selected by Miss Allen on the basis of no defective deciduous teeth and high incidence of defective deciduous teeth, was undertaken. The dental data upon which the statistical analysis and this preliminary study are based have been collected under the direction of Dr. Frederick C. Allen of the Forsyth Dental Infirmary.5 The groups selected represent Group I, those children who have reached six and one-half years of age with no defective teeth; Group II, those children with the highest incidence of defective deciduous teeth at three years of age; and Group III, those children who had perfect teeth at three years of age but developed the highest incidence of defective teeth by four years of age. This preliminary study of these three groups was undertaken to discover what, if any, significant differences could be found in these groups of children which might explain why some children were able to go through as much as six and one-half years of life with no defective deciduous teeth, while others of our children showed a high incidence of defective teeth by three years of age. The more significant differences seem on this small number of cases to appear in the field of nutrition or in factors related to nutrition. In this preliminary study each case has been considered individually in considerable detail. All of the material presented in the charts which follow has been independently collected and analyzed by those of