Cross-sectional studies suggest that postnatal blood lead concentrations (PbB) are negatively associated with child growth. Few studies prospectively examined this association in populations with low PbB. We investigated longitudinal associations of childhood PbB and subsequent anthropometric measurements in a multi-ethnic cohort of girls. Data were from The Breast Cancer and Environment Research Program at three US sites: New York City, Cincinnati, and San Francisco Bay. Girls were enrolled at ages 6-8 years in 2004-2007. Girls with PbB collected at ≤10 years old (mean 7.8 years, standard deviation (SD) 0.82) and ≥3 follow-up visits were included (n=686). The geometric mean of PbB was 1.03 ug/dL (95% Confidence Interval (CI): 0.99, 1.06) and was dichotomized as “low”, <1 ug/dL (n=344) and “high”, ≥1 ug/dL (n=342). Anthropometric measurements of height, body mass index (BMI), waist circumference (WC), and percent body fat (%BF) were collected at enrollment and follow-up visits through 2015. Linear mixed effects regression, adjusted for race/ethnicity, estimated how PbB related to changes in girls’ measurements from ages 7-14 years. At 7 years, mean difference in height was -2.1 cm (95% CI: -3.1, -1.0) for girls with high versus low PbB; differences decreased with age to -1.4 cm (95% CI: -2.5, -0.33) at 14 years. Mean differences for BMI, WC, and BF% at 7 years between girls with high versus low PbB were -0.82 kg/m2 (95% CI: -1.3, -0.30), -2.3 cm (95% CI: -3.9, -0.65), and -2.2% (95% CI: -3.6, -0.76), respectively. Overall, these differences persisted or decreased with advancing age and at 14 years, differences were -0.69 kg/m2 (95% CI: -1.5, 0.08), -2.8 cm (95% CI: -4.9, -0.70), and -1.6% (95% CI: -2.9, -0.24) for BMI, WC, and BF%, respectively. These findings suggest that higher levels of PbB during childhood, even though relatively low by screening standards, may be inversely associated with anthropometric measurements in girls throughout early adolescence.