Most studies focusing on the relationship between physical activity and obesity have been conducted in middle class Caucasian adults and children and few such studies are available concerning minority children in physical activity settings (Johnson, Kulinna, Tudor-Locke, Darst, & Pangrazi, 2007; Rowlands et al., 1999; Tudor-Locke, Lee, Morgan, Beighle, & Pangrazi, 2006; Tudor-Locke, Pangrazi, & Corbin, 2004). To address this issue, the current study examined the relationship between pedometer-based physical activity level (i.e., step counts) and body composition (i.e. Body Mass Index [BMI]) among low socio-economic minority children in an after-school physical activity program. Participants included 131 students in grades 3-6 (64 boys and 67 girls) from one public elementary school. To assess each gender's BMI and physical activity level, they were instructed to carry the pedometers for the entire after-school physical activity class time for six consecutive lessons. Pearson correlation and regression analysis indicates that there was an inverse and significant relationship between both genders' pedometer-based physical activity level and their BMI. One-way ANOVA tests identified statistically significant differences between step counts and BMI mean scores. Results provided empirical evidence that such a relationship existed among this group of minority children. This study also confirms previous findings that boys are more active than girls (p less than 0.01) and girls have higher BMI than boys (p less than 0.01). Therefore, this study suggests that more attention should be provided related to intervention studies in girls. (Contains 2 tables and 2 figures.)