This paper starts from the idea that children learn and construct gendered identities within local communities of masculinity and femininity practice, including peer communities. The data presented come from an ESRC-funded study of tomboy identities, which investigated the enabling and constraining factors for girls in taking up and maintaining tomboy identities, and the relationship between these and the perpetuation of active girlhood during the later primary school years. The paper considers how gender is constructed within the physical spaces of school playgrounds. We contrast the spatialities of the two research sites--one, an inner-city school with restricted playground space; the other, an outer-London school with extensive grounds--and examine the implications of these for children's activities and associated identities. We show how the spaces of the school and the surrounding area are factors in the children's construction of their identities, and how playground space is used partly to construct and maintain gender difference by both girls and boys. In particular, we examine how children use play as a means to the construction of their masculinities and femininities, and how these are enabled and constrained by their peer communities. (Contains 3 notes.)