Despite progress made toward increasing women's interest and involvement in science, technology, engineering, and math (STEM), women continue to be underrepresented and experience less equity and inclusion in some STEM fields. In this article, I review the psychological literature relevant to understanding and mitigating women's lower fit and inclusion in STEM. Person-level explanations concerning women's abilities, interests, and self-efficacy are insufficient for explaining these persistent gaps. Rather, women's relatively lower interest in male-dominated STEM careers such as computer science and engineering is likely to be constrained by gender stereotypes. These gender stereotypes erode women's ability to experience self-concept fit, goal fit, and/or social fit. Such effects occur independently of intentional interpersonal biases and discrimination, and yet they create systemic barriers to women's attraction to, integration in, and advancement in STEM. Dismantling these systemic barriers requires a multifaceted approach to changing organizational and educational cultures at the institutional, interpersonal, and individual level.