This document describes a school-based intervention program aimed at decreasing body weight by 7% and increasing physical activity by 120 minutes per week in ethnically diverse children ages 12-18. The 6-month afterschool program, implemented through the Boys and Girls Club, uses hands-on activities like Zumba, sports, and cooking classes along with workshops on health risks and nutrition to promote behavioral changes around physical activity and nutrition using Social Cognitive Theory and the Health Belief Model. Program completion is rewarded with gift cards and Disneyland tickets to increase participation and maintenance of healthy behaviors.