OBJECTIVES: African-American girls are at increased risk for becoming overweight. Increased physical activity may prevent this. This study examines measurements of girls' physical activity and associations with: BMI, parent's reported self-efficacy and support for helping daughters be active, girl's perceived support from parents for physical activity, parent's and girl's perceived neighborhood safety and access to facilities, and family environment. RESEARCH METHODS AND PROCEDURES: Fifty-two 8- to 10-year-old African-American girls and their primary caregiver in the Minneapolis/St. Paul area participated in the Girls Health Enrichment Multisite Studies pilot intervention to prevent weight gain by promoting healthy eating and physical activity. Data collected included height, weight, physical activity level, and physical activity-related psychosocial measures from girl and parent. Girls wore an activity monitor for 3 days to assess activity level. Correlations were computed among the average minutes per day of moderate to vigorous activity between 12 pm and 6 pm and BMI and psychosocial measures. RESULTS: BMI was inversely correlated with moderate to vigorous activity (r = -0.35, p < 0.01), whereas parent's self-efficacy for supporting daughter to be active was positively correlated with activity (r = 0.45, p < 0.001). There was a trend for parent's reported support of daughter's activity level to be associated with activity (r = 0.26, p < 0.06). Girl's perception of parent's support for physical activity, perceived neighborhood safety and access to facilities, and family environment were not associated with girl's activity levels. DISCUSSION: Interventions to increase physical activity among preadolescent African-American girls may benefit from a parental component to encourage support and self-efficacy for daughters' physical activity.