Research on free play among children is reviewed, and the relation of such research to the adaptation and use of play environments for multiply handicapped/mentally retarded (MH/MR) children is considered. Noted among research findings are that the nature and organization of playground equipment has a significant effect on children; that children prefer equipment that is either movable and/or complex; and that the creative playground can stimulate and provide for as much, if not more, gross motor activity as the traditional playground. It is concluded that play meets many basic needs of the children: acceptance, achievement, creativity, emotional development, social growth, and physical development. (SBH)