OBJECTIVE To define racial differences in lipoprotein and apolipoprotein levels in girls aged 9 to 10 years. METHODS Baseline analysis of a prospective cohort study. METHODS Three clinical sites. METHODS A total of 1871 black and white girls, aged 9 to 10 years, with complete maturation data (pubic hair and areolar development and menarche) and an 8-hour fast before blood draw. METHODS Anthropometric measures and serum lipid, lipoprotein, and apolipoprotein levels. RESULTS All analyses were adjusted for maturational differences between blacks and whites (areolar or pubic hair development and menarche). The mean body mass index was marginally higher in black girls than in white girls (18.9 vs 18.3 kg/m2; P = .002), while the sum of skinfolds (34.5 vs 34.8 mm; P = .77) was equivalent. However, both body mass measures were skewed higher at the upper percentiles in black girls. The low-density lipoprotein cholesterol level was similar between black and white girls. Mean triglyceride values were higher in white girls than in black girls (0.92 vs 0.79 mmol/L [81 vs 70 mg/dL]; P < .001); however, these differences were most pronounced in the upper percentiles. Conversely, mean high-density lipoprotein cholesterol and apolipoprotein A-I levels were higher in black girls than in white girls (1.44 vs 1.37 mmol/L [56 vs 39 mg/dL] and 147 vs 138 mg/dL, respectively; both P < .001); and again the differences were most evident at the upper end of the distributions. CONCLUSIONS Racial differences in the mean levels of triglycerides, high-density lipoprotein cholesterol, and body mass in girls in the National Heart, Lung, and Blood Institute Growth and Health Study (NGHS) at age 9 to 10 years were predominantly the result of differences observed at the upper end of the distributions. The reported black-white differences for mean high-density and low-density lipoprotein cholesterol and triglyceride levels in adult women are comparable to NGHS results. Distributional characteristics of these risk factors as well as trends in lipids, lipoproteins, and apolipoproteins, will be evaluated in an ongoing longitudinal assessment that covers the full maturational period.