Gender is arguably the most salient and important social category for children. It is one of the first descriptors they learn about themselves. By the time they are in preschool, they have attitudes and stereotypes about how boys and girls should look, think, and behave. This entry offers an overview of gender in childhood. It covers what children know and how children think about gender, what gender differences exist between boys and girls, how children learn about gender and gender stereotypes, and how gender affects the emotional, social, and academic development of children.