In several brief sections, this pamphlet defines play, discusses how play helps a child develop, and how play changes as a child grows older, indicates the role of toys and certain play activities in promoting sex stereotypes, and identifies the role of fantasy and imagination in children's play. A discussion of the role of parents in fostering their children's play concludes the pamphlet. The pamphlet, one of a series produced by the Division of Scientific and Public Information, National Institute of Mental Health, is designed primarily to help parents care for their children and themselves in ways that promote good mental health. However, the pamphlet may sometimes be useful for others, such as relatives, school teachers, and babysitters, who play important roles in the lives of children. (Author/RH)