This study examined the physical size and subcutaneous body fat of 269 Caucasian boys and girls, ages 3, 4, 5, and 6. In addition to height, weight, and leg length, the measurements included seven diameter, eight circumference, and five skinfold measurements. The means and standard deviations for all anthropometric measurements are presented. When compared by age group, the children were significantly different (p < .01) on all physical size measurements, but not on the skinfold measurements. When the measurements were analyzed to determine significant sex differences, it was evident that, where differences existed, the boys' physical size measurements were larger than the girls', while on the other hand, the girls had a greater amount of subcutaneous body fat than did the boys. The anthropometric data reported in this study did not support the secular trend phenomenon, but substantiated the contention that between three and six years of age, the triceps skinfold measurement declines gradually for boys and remains stable for girls. In summary, it is imperative that anthropometric measurement standards be continually revised and kept current, and that when possible, children be individually evaluated for classification into groups and not classified solely on the basis of age and sex.