This study examined the effects of sex, structure, and social interaction on 18 white middle class children, nine boys and nine girls, attending a daycare center. The children were observed over a 6-week period during a 2 1/2-hour free-play time. Results showed that both sexes equally apportion all types of free-play time behavior, show the same amount of make-believe play, and identically utilize a given play area (such as householding or blocks/trucks) for make-believe. Different play areas generated different amounts of make-believe, with the household areas generating the most make-believe. In addition, make-believe in the household area was found to elicit a greater proportion of social interaction than other types of behavior and other play areas. The only sex difference found was that boys engage in more make-believe than girls in nonstructured areas like open floor spaces. It is suggested that these findings seem to disconfirm various modeling hypotheses. Educational implications of the findings are discussed. (MS)