We draw on public observations conducted in a zoo to identify three instances in which adults make use of its specific spatial and symbolic resources to transmit socialization messages to children according to "naturalized" models of hegemonic gender difference. First, adults attribute gender to zoo animals by projecting onto them human characteristics associated with feminine and masculine stereotypes. Second, adults mobilize zoo exhibits as props for modeling their own normative gender displays in the presence of children. Third, adults discipline boys and girls differently in the context of the zoo’s built environment, and in doing so, they communicate socialization messages to children regarding how to behave in conventionally gendered ways. In emphasizing the context of the zoo as a site for the naturalization of gender categories, we identify how adults transmit gender socialization messages to children that promote gender stereotypes associated with the biological determinism of the natural living world.