Because of the role of play in the epigenetic construction of social brain functions, the young of all mammalian species need su?fficient play. For the same reason, the nature of that play becomes an important social policy issue for early childhood development and education. Animal research on this topic indicates that play can facilitate the maturation of behavioral inhibition in growing animals, while psychostimulants reduce playfulness. Our failure to provide adequate opportunities for natural play in modern societies, the author argues, may have contributed to the steady growth in the diagnosis of Attention De?ficit Hyperactivity Disorders (ADHD) in children, which in turn has increased prescriptions of highly e?ffective attention-promoting psychostimulants whose developmental e?ffects on growing brains remain unclear. ?The author concludes that the incidence of ADHD--and hence the need for psychostimulant medications for growing children--may diminish if we create play sanctuaries for preschool children, where they could play naturally with each other, and thereby facilitate frontal lobe maturation and the healthy development of pro-social minds. Physical play should be part of the daily social diet of all children throughout grade school.