Data for this study were seriatim measures of stature on United States youths of North European ancestry. They were gathered between 1925 and 1932 in Massachusetts and between 1950 and 1957 in Iowa. Statistics from size and velocity analyses for each period were obtained and compared. At age 10 years, mean stature of the 1950-1957 youths exceeded that of the 1925-1932 youths by more than 5.0 cm. It was deduced that less than 2.0 cm of this amount arose from a difference in socioeconomic composition of the samples, and upwards of 3.0 cm from secular increase. In both periods, annual velocity means increased between ages 9 years and 12 years for females and between 11 years and 14 years for males. These increases were greater from the velocity data for 1950-1957 than for 1925-1932. No predictive relationship was found between stature at a pre-adolescent age and early occurrence of adolescent peak velocity for stature.