This study examined a model suggesting that personal variables (age and gender) and environmental variables (activity centers) affect social-cognitive aspects of children's play. A total of 80 children (32 boys and 48 girls) participated. Same-age and same-gender dyads from each of two age groups (4- and 5-year-olds) were observed playing in an experimental playroom. On two occasions, children played in a dramatic center and on two occasions in a blocks center. Social-cognitive aspects of play were scored according to a time-sampling procedure and were concurrently scored on a nested social-cognitive matrix with an additional listing for onlooking, unoccupied, and rough-and-tumble behaviors. Results were compatible with those suggested by the model. Specifically, play generally followed the themes suggested by the props in each of the two centers. Predicted age effects were supported to the extent that play became more complex with age. Gender interacted with age and activity center to cause variation in play. Main effects due to gender were, however, unreliable. Results were considered significant in that they document the main and interactive effects of personal and controlled environmental variables on preschoolers' play behaviors. (Author/RH)