OBJECTIVE: To estimate the prevalence and incidence of overweight in African-American and Caucasian girls, and to examine associations between adolescent overweight and cardiovascular disease (CVD) risk factors. STUDY DESIGN: In the National Heart, Lung and Blood Institute Growth and Health Study (NGHS), annual measurements were obtained from girls followed longitudinally between age 9 or 10 and 18 years; self-reported measures were obtained at age 21 to 23 years. A total of 1166 Caucasian girls and 1213 African-American girls participated in the study. Childhood overweight as defined by the Centers for Disease Control and Prevention (CDC) was the independent variable of primary interest. Measured outcomes included blood pressure and lipid levels. RESULTS: Rates of overweight increased through adolescence from 7% to 10% in the Caucasian girls and from 17% to 24% in the African-American girls. The incidence of overweight was greater at age 9 to 12 than in later adolescence. Girls who were overweight during childhood were 11 to 30 times more likely to be obese in young adulthood. Overweight was significantly associated with increased percent body fat, sum of skinfolds and waist circumference measurements, and unhealthful systolic and diastolic blood pressure, high-density lipoprotein cholesterol, and triglyceride levels. CONCLUSION: A relationship between CVD risk factors and CDC-defined overweight is present at age 9.