Preschool is a crucial time for obesity prevention, as children are developing eating and physical activity habits. A lack of physical activity at preschool may contribute more to overweight children than parental influences such as modeling and supporting physical activity or providing fitness equipment in the home. Let Me Play is a comprehensive program implemented in Head Start classrooms in various locations across the country, offering training to teachers, and providing them with developmentally appropriate physical activities that can be easily incorporated into existing curriculum. (Contains 2 figures.)