This study investigates the interaction of three cognitive (functional, constructive, dramatic) and three social (solitary, parallel, group) dimensions of free play activities and their stability over time among boys and girls in a preschool setting. Subjects were 18 children attending a university preschool in Southwestern Ontario. Data for each child were collected in 1-minute daily observations for two 3-week periods, three months apart. Analysis of variance indicated that four activities changed in duration over time but preferred activities remained nearly identical. Cognitive dimensions of play with vehicles and blocks differed over time. Males played more with vehicles and sand and water, and spent less time in painting and art construction than females. Findings for sex and types of play in a particular activity were stable over time. The degree of "freedom" in free play appears to be influenced by available materials. For instance, group and dramatic play may be inhibited by the availability of art activities, which appears to encourage non-social and constructive behaviors. Findings are seen to validate results of earlier studies on children's free play activities. Implications for educational programs and recommendations for further research are indicated. (Author/RH)