This study examined associations between personal, family, and peer variables on objectively measured physical activity (PA), and sports participation, of African American, Latino, and white girls. Specific variables included barriers efficacy, parent PA, parent support of PA, the home exercise environment, friends’ PA, and friends’ support of PA. The sample comprised 372 girls (mean age = 12.03 years; SD = 1.81; n = 128 African American, n = 120 Latino, and n = 124 white). Data were analyzed using multiple-sample structural equation models (by ethnicity), controlling for age, household income, body mass index, and physical development. Girls’ moderate to vigorous PA (MVPA) was positively related to friends’ support for all groups, and to parent PA only for African American girls. For sports, greater parental support related to more participation across ethnic/racial groups, whereas friends’ support was important only for African American girls. Age and physical development were negatively related to MVPA, and higher income was associated with greater sports participation. Numerous significant correlations emerged between the independent variables, with some differences across racial/ethnic groups. Findings highlight the role of parent and friends’ support for both MVPA and sports participation of early adolescent girls, as well as the importance of determining PA correlates among different ethnic/racial subgroups
