The design involves randomization of 200 African American girls, eight to 10 years of age into intervention or control groups. After one year, the groups are compared to test the primary hypothesis that a one year afternoon exercise program will reduce accretion of general and visceral adiposity in these girls. Then the girls will switch group assignments for the next year. The pattern of data over the three time points will show what happens over a two year period in which the youths are, or are not, involved in the exercise program. The measurements will include: (1) percent body fat with dual-energy x-ray absorptiometry; (2) visceral adipose tissue (VAT) with magnetic resonance imaging; (3) cardiovascular fitness with a multi-stage treadmill test; (4) cardiovascular disease (CVD) risk factors (i.e., the ratio of total to high density lipoprotein cholesterol, insulin, systolic blood pressure, and fibrinogen); (5) free-living exercise and diet; (6) psychosocial variables (i.e., self-efficacy and self-concept); (7) sexual maturation; (8) anthropometric measures. The exercise program will be implemented in neighborhood schools for 90 minutes each weekday afternoon. Transportation will be provided if needed. Sessions will include motor skill instruction and aerobic exercises.