The number of obese children in the US remains high, which is problematic due to the mental, physical, and academic effects of obesity on child health. Data indicate that school-age children, particularly underserved children, experience unhealthy gains in BMI at a rate nearly twice as fast during the summer months. Few efforts have been directed at implementing evidence-based programming to prevent excess weight gain during the summer recess. Camp NERF is an 8-week, multi-component (nutrition, physical activity, and mental health), theory-based program for underserved school-age children in grades Kindergarten - 5th coupled with the USDA Summer Food Service Program. Twelve eligible elementary school sites will be randomized to one of the three programming groups: 1) Active Control (non-nutrition, physical activity, or mental health); 2) Standard Care (nutrition and physical activity); or 3) Enhanced Care (nutrition, physical activity, and mental health) programming. Anthropometric, behavioral, and psychosocial data will be collected from child-caregiver dyads pre- and post-intervention. Site-specific characteristics and process evaluation measures will also be collected. This is the first, evidence-based intervention to address the issue of weight gain during the summer months among underserved, school-aged children. Results from this study will provide researchers, practitioners, and public health professionals with insight on evidence-based programming to aid in childhood obesity prevention during this particular window of risk. NCT02908230/09-19-2016