The development of body fatness and leanness is examined in an ongoing prospective nutrition and growth study. Individual skinfold thicknesses, relative weights, weight gains, activity levels, and caloric intakes were examined at seven ages between 6 months and 9 years. Changes in body fatness in this group of children provide evidence that the obese infant usually does not become the obese child. Weight gain in infancy is also a poor predictor of 9-year old obesity. Changes from obese to non-obese or lean are often not linear. There is evidence that impending or actual obesity begins at ages 6 to 9 years with some predictability provided as early as age 2 years for girls, age 3 years for boys.