This paper draws together briefly theories and knowledge from research in morphology and cognitive psychology, as well as some hypothetical information from traditional psychiatry, to show the ramifications of play in children's development. Play is defined as any of a wide variety of behaviors through which an individual attempts to discover what sort of person he is, what he is able to do, and in this way learn about his environment. Play is said to: (1) help the infant to understand the potentialities of its own body, of its body in space, of the way in which stimuli will impinge upon it, and how it must organize itself in relationship to these incoming stimuli; (2) offer the opportunity for the child to "chunk" incoming information; (3) provide environmental learning and the opportunity for mastery; (4) help the infant acquire information about his potential creativity, his imagination, and his social skills through imitation and role-playing; (5) help the equilibration process, and ensures the use of developing schemata; (6) help the child distinguish the "not me," and allows him to begin to recognize what is outside of his omnipotent and narcissistic control; (7) help the "observing ego" and act as a kind of self-healing mechanism. (Author/SS)