This paper examines the associations between the food and physical activity environment in schools and body mass index (BMI) for lower-income boys and girls when they were in the 8th grade during 2007. Analyzing secondary data from the nationally representative Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999 (ECLS-K), researchers found that a number of student physical activity and food choices were associated with BMI. Participating in school sports was associated with BMI scores for lower-income boys that were 0.55 points lower than for boys who did not participate in school sports. For lower-income girls, eating school breakfast was associated with a 0.70 higher BMI score and eating school lunch was associated with a 0.65 higher BMI score. The findings suggest that schools may influence adolescent BMI and there is room for improvement in school food and physical activity environments to promote healthier weights among lower-income boys and girls.