A preliminary version of this work was presented at the 10th National Conference on Child Health Psychology in Gainesville, Florida, April 20, 2006. This study tested the effect of a structured aerobic exercise program on anger expression in healthy overweight children. Overweight sedentary children were randomly assigned to an aerobic exercise program or a no-exercise control condition. All children completed the Pediatric Anger Expression Scale at baseline and posttest. Anger Out and Anger Expression scores were lower for the exercise condition at posttest. Fitness improvements contributed significantly to final models, and points earned for adherence correlated negatively with posttest Anger Out. An aerobic exercise program might be an effective strategy to reduce anger expression, including reduction of aggressive behavior, in overweight children.