Increased numbers of young children who are overweight have become a significant health problem in the United States. Public health investigators have hypothesized that increased caloric intake and low levels of physical activity may be associated with the troubling trend of weight problems among children. To enhance preschool children's moderate to vigorous physical activity on playgrounds the authors develop, implement, and evaluate two practical teacher-implemented activities. Direct observations of five children in two preschool programs during teacher-implemented activities indicate increased moderate to vigorous physical activity on intervention days relative to nonintervention days (i.e., business-as-usual conditions). The results and implications for preschool practitioners are discussed. (Contains 2 tables and 2 figures.)