This article surveys the research on gender role development and stereotyping in preschool programs, gender segregation and theories concerning the origins of gender role, and sex differences in play activities and behavioral styles with implications for the child’s social development. The findings on behavioral differences in terms of the child’s own attempts to understand gender roles, the difference in boys’ and girls’ reactions to teacher-structured activities with implications for future school performance, and interventions meant to decrease sex differences are discussed. Suggestions are made regarding the design of programs to increase the child’s participation in varied activities.