Stereotypes associating math more with men and boys than women and girls have been identified as a contributing factor to women’s underrepresentation in Science, Technology, Engineering, and Math fields. Unfortunately, these stereotypes emerge as early as elementary school and begin to shape young girls’ math achievement and interest. This chapter documents the sources both in and outside of the school environment that contribute to the development of these stereotypes and reviews evidence of the relationship between children’s stereotypes and their math achievement. Furthermore, this chapter discusses recent research on interventions to increase young girls’ engagement in math-related fields. Strategies are provided for caregivers and educators to help change stereotypes about math and gender and disrupt the impact of these stereotypes on girls’ behavior.