Little attention has been given to the developmental process of "how children learn to move" and the changing role that emerging motor competence may play in children and youths' physical activity levels as they grow. But we need to recognize that there is a developmental trajectory to physical activity and the factors that affect it if we are going to get urban youths to be physically active. This article discusses the role that motor competence can play in promoting and sustaining youth physical activity and describes how motor competence can be improved in young children.