This study examined how children's play varied as function of child's sex, play partner's sex, and whether they played in dyads or groups. Observation data revealed that boys' same-sex play was more active-forceful, farther from presence of adults, and more stereotyped than girls', a pattern exaggerated in groups. Mixed-sex play was more likely than other configurations to occur near adults and was intermediate in active-forceful and stereotyped activities. (Author/KB)