Among 85 members of 12 Old American families in which four generations were measured at Harvard, there were 12 fathers, 24 sons, 30 grandsons, and 19 great-grandsons. Mean birthdates for the four generations were 1858, 1888, 1918, and 1941, and mean ages when measured were 21.9, 19.0, 18.9, and 18.8 years. There was a significant increase in height between generations I and II (2.63 cm, p<0.02), a smaller rise (1.14 cm, not significant) to generation III, and no rise at all to generation IV. Weight rose negligibly until generation III and then increased 1.9 kg (not significant) to generation IV. The ponderal index, height/, rose slightly to generation III, then fell significantly (p<0.02) in generation IV to its original value in generation I. These findings confirm other indications that the secular increase in height has ended among economically-favored Americans. Weight, on the other hand, may still be increasing.