Background: The purpose of this research was to examine the impact of school-related variables on the physical activity (PA) levels of early adolescent African American, Latino, and White girls. Methods: Data were collected from 353 African American (N?=?123), Latino (N?=?118), and White (N?=?112) girls. Physical activity levels included a PA latent factor and minutes per day of moderate-to-vigorous physical activity (MVPA). School variables included hours of physical education (PE), PE enjoyment, school physical environment, recess activity, and active transport to/from school. Multiple-group structural equation modeling examined relations between school variables and PA across ethnic groups. Results: Hours of PE were positively related to higher PA factor scores. Active transport was related to higher PA factor scores for White girls only, and to greater MVPA for African American girls only. Hours of PE were related to PE enjoyment and the school physical environment for some ethnic groups. Physical education enjoyment was related to more recess activity among African American and Latino girls, and PE enjoyment was associated with more active transport to school for all girls. Conclusions: Physical education participation and active transport significantly contribute to girls' levels of PA, with differences across ethnic groups.