This study explored a community-based after-school program's effect on obesity in minority children. Study participants included 178 third through fifth graders (47% Latino, 25% Asian, and 18% African-American) enrolled in America SCORES Bay Area. Outcomes were attendance, change in fitness (20-meter shuttle test), and body mass index (BMI) z-score over eight months. At baseline, 52 percent of children were overweight or obese. Children attended SCORES > 4 days/week and fitness significantly improved (p < 0.01). BMI z-score decreased by 0.04 (p = 0.10) overall, and by 0.05 (p = 0.08) among obese children, but increased among African-American children. These results suggest that SCORES increases fitness and may improve BMI in some minority children. Effect modification by race may relate to differential growth patterns or engagement in SCORES. These findings suggest community-based programs could effectively address obesity. A randomized trial of the SCORES program is warranted to rigorously examine this type of after-school program's impact on child health.