This dissertation studies preschool teachers’ perceptions of children’s performance of femininity and masculinity in kindergarten. The in-depth interviews brought to light several gender stereotypes based on the constant hetero-determination of femininity and masculinity. The participant kindergarten teachers did not manage to avoid the gender stereotypes when they talked about children’s characteristics, their preferred activities, and their interactions both with each other and with their teachers. At the same time, the construction of their gender identity was approached in terms of environmental and biological influences, with children not actively involved in this process. When they identify gender stereotypes, participant kindergarten teachers stated that they engage in several practices to eliminate them, without, however, planning specific interventions or collaborating with the children themselves, implying that any action of theirs is spontaneous and based on the unequal power relations between educators and students in the classrooms.