The present data are based on thirty-five physical measurements for a good sampling of preschool children. Differences in the Observa tions Of two technicians are analyzed and, for some. Measurements, between two observations by the same technician. Of special interest are Dr. Knott's estimates of the approximate frequency of measurement considered profitable during the preschool years: stature, ten times a year; hip, width, sitting height, leg girth, and total arm length, three to four times a year; head, chest depth and elbow width, every two years; and the remaining measurements chiefly once a year. The study, as a whole, forms a unit in the anthropometric program being carried on in the Station by Dr. Howard V. Meredith.