Clinically normal baboons (Papio cynocephalus anubis [Kingfjdon, 1971]) were used in an experiment which (1) examined growth in 48 subjects randomly assigned to three diet treatments (LC = low calorie; MC = medium calorie; HC = high calorie); (2) tested the hypothesis that different amounts of caloric availability during the neonatal period (birth to 16 weeks) had a significant effect on growth and development as measured by weight, crown-rump length, and triceps circumference in the subsequent infant, juvenile, and adolescent periods; (3) evaluated the rate of growth in these subjects; and (4) evaluated the extent to which they were capable of canalization (catch-up and catch-down growth). The LC subjects were fed 40% fewer calories than MC subjects and HC subjects were fed 40% more calories than MC subjects. Early in life baboon growth was influenced by caloric shortages and excesses. Canalization of growth attainment occurred in both the LC and HC infants after preweaning dietary treatments had ceased. This suggested that removal of environmental (caloric) insults allowed growth to be regulated by its genetic component (developmental canalization) and to return to a more normal growth pattern. Catch-up growth of LC infants occurred by 26 weeks. Catch-down growth of HC infants to normal levels occurred by 26 weeks. This indicates that growth canalization can work in both directions (reduction from caloric excess and increase from caloric insufficiency) within the same time frame. Following infancy, there were few significant treatment differences in growth of males, whereas females retain the effects of neonatal dietary treatments throughout the 5-year study.