A study investigated the effects of symbolic play treated as a mediator for increasing language comprehension and facilitating oral language growth. The study included two aspects of language: language comprehension and language development. Independent variables were forms of play--puppet action, body action, abstract (imagined) action, and no action (control); age; and sex. Dependent measures were cloze comprehension, 10-item measures for language comprehension, and the students' connected discourse scored t-units for language development. Subjects were 80 five-year-olds and 80 seven-year-olds. After no significant main or interaction effects on preassessment language measure between the factors were found and after the treatments were completed, major findings were as follows: (1) on the cloze measure of language comprehension, children in the body action play group received significantly higher mean scores than did those in the abstract action play and control groups; (2) on the question measure of language comprehension, five-year-olds in the puppet action and body action play groups received significantly higher mean scores than did the five-year-olds in the abstract action and play groups; and (3) on the t-unit measure of language development, the seven-year-olds received significantly higher mean scores than did the five-year-olds. There were no significant effects for sex. (Author/HTH)