Walking to school is one of the objectives for children and adolescents in Healthy People 2010 and in previous studies was associated with higher levels of overall physical activity, which has been shown to decrease obesity. Therefore, more children walking to school should result in increased physical activity and presumably reduce obesity. However, increasing child pedestrian activity could increase the risk of child pedestrian injuries. Walking with an adult who provides instruction in pedestrian skills and monitors the child's actual behavior may be the most important component of a successful intervention. Walking with an adult reduced child pedestrian injury risk by almost 70%. A walking school bus (WSB) addresses safety concerns by providing a period of physical activity supervised by several responsible adults and teaching opportunities around pedestrian safety skills on the way to and from school. Children may join the WSB at various points along the set route. Despite the growing popularity of WSB programs in the United States, randomized, controlled-studies are lacking that examine the impact on children's safety, physical activity, and health. We seek to help fill this gap in the literature by piloting a WSB program in elementary schools in the Houston Independent School District to test feasibility. We hypothesize that a WSB program will: (1) increase the number of students walking to school and decrease the number of students driven to school by car, (2) increase students' pedestrian safety behaviors (3) increase students' physical activity, and (4) decrease students' excess weight gain.