Students of child psychology have emphasized the periodicity of the play behavior of children of different ages and have investigated the forms of play which are characteristic of each age. It is the purpose of this paper to bring together in systematic form the studies which relate to the play of the different stages of development from birth to maturity.Among writers, there is no agreement as to how many play periods there are in the child's development, what names shall be applied to these periods nor how long each one of them lasts. Among the best classifications of age periods in play behavior are those of Baldwin (8), Croswell (31), Curtis (32), Gulick (50), Johnson (66), King (70), Kirkpatrick (71), Lee (72), Lehman and Witty (80), Pyle (103), Puffer (102), Reaney (104), and Wood (128).Several investigators have attempted to explain the periodicity of play in terms of its causes. Lee (72), Waddle (123), and Norsworthy and Whitley (98) ascribe the different plays of different ages to "instincts." Blanchard (10) and Gulick (50) maintain that the child's play interests depend upon chronological age, physiological age, mental age and environmental situations. Lehman and Wilkerson (78) report that chronological age is more powerful than mental age in determining the child's play behavior. Reaney (104) has subdivided the play of the childhood years into four different periods, based upon chronological age. Many investigators have stressed the fact that the transition from one form of play to another is gradual and often barely perceptible. Curtis (32), Lee (72), and Lehman and Witty (80) point out that the different play periods are not separated by distinct dividing lines.In the classification of play, the following stages of development have been arbitrarily used by the writer: (1) Babyhood (birth to three years) ; (2) Childhood (three to six years) ; (3) Youth (six to eleven or twelve years); (4) Adolescence (eleven or twelve ta twenty-one years).