THE USE OF PLAY THERAPY WITH MENTALLY SUBNORMAL CHILDREN IS EXPLORED, AS IT ENABLES SUCH CHILDREN TO REALIZE THEIR POTENTIALS AND TO INTERACT MORE ADEQUATELY WITH THEIR ENVIRONMENT. A CONSIDERATION OF GENERAL AND THEORETICAL PROBLEMS AND A CONCEPTION OF THE DEVELOPMENT OF MAN'S ESSENTIAL QUALITIES ARE PRESENTED. A GENERALIZED THEORY OF PLAY THERAPY IS ESTABLISHED AND RELATED TO THE LEARNING PROCESS. THEORETICAL IMPLICATIONS OF PLAY THERAPY APPROPRIATE FOR SUBNORMAL CHILDREN ARE DISCUSSED. TECHNIQUES AND PROCEDURES OF PLAY THERAPY ARE EXAMINED. DESCRIPTIONS ARE GIVEN OF VARIOUS METHODS WHICH USE COMBINATIONS OF STRUCTURED OR UNSTRUCTURED MATERIALS AND STRUCTURED OR UNSTRUCTURED TECHNIQUES. TECHNIQUES OF DIAGNOSIS AND EVALUATION EMPLOYING PLAY THERAPY ARE CONSIDERED. INDICATION IS MADE OF THE USE OF VARIOUS TYPES OF PLAY THERAPIES IN REFERENCE TO THE CHILD'S ADAPTIVE BEHAVIOR, INTELLIGENCE, AND HIS RELATIONSHIP TO HIS ENVIRONMENT. PLAY THERAPY AS RELATED TO OTHER POSSIBLE TREATMENT MODALITIES, DIAGNOSIS, AND RESEARCH IS ALSO DISCUSSED. REFERENCES ARE PROVIDED. THIS DOCUMENT WAS PUBLISHED BY GRUNE/STRATTON, INC., 381 FOURTH AVENUE, NEW YORK, NEW YORK 10010, AND IS AVAILABLE FOR $7.75. (MU)