The dissertation Teacher, is there firewomen? Girls and boys coconstruing gender identities at school investigates the construction of gender identities among 6 and 7 years old children, first graders of a public school at Rio de Janeiro city, through the analysis of talk in interaction in mixed groups, during game activities controled by the children, and in sharing activities, with teacher participation. This ethnographic research articulates Interactional Sociolinguistics and Conversation Analysis (discursive topics, participation structures, frames, and footings analyses), through a dialogue among 80´s and 90´s gender theories, as well as gender and childhood studies, focusing context studies (cultural, school, types of activities). The data analysis points to the construction of different female and male gender identities, giving rise to macro issues related to the theory of difference, and to different male and female identities according to types of school activities. There is also a difference concerning individual and group identity constructions. Thus, I discuss the ways of being a girl or a boy that those children co-construed, reflecting on gender theories of dominance, of difference, constructivist, and performative. I evaluate if the results reproduce hegemonic models of pre-established identities, or if they reformulate/reconstrue other forms of being girls and boys, considering the context and the different types of activities that those children engage in.