Children's play activities are studied as a form of associative material showing the significance of spatial configurations in the expression of dynamic relationships of shapes, sizes and distances. Detailed accounts, with drawings, of play with toys are given and discussed in relation to the child's clinical problems as expressed by the course of his play activity. An experiment is described in which college people are asked to use toys to construct dramatic scenes. Analyses of these disclosed them as products of traumatic tension rather than dramatic products, just as in the experiments with children. The explanation of this may be that the play material evoked the spirit of infantile conflict. The usefulness of this sort of play study lies in its possibility of furnishing a means of understanding the prelinguistic and alinguistic strata of the human mind.