We draw from ecological systems and social psychological theories to elucidate macrosystem‐ and microsystem‐level variables that promote and maintain gender inequities in science, technology, engineering, and math (STEM). Because gender‐STEM stereotypes undermine girls’ (and women's), but boosts boys’ (and men's), STEM interest and success, we review how they operate in STEM learning environments to differentially socialize girls and boys and undermine gender integroup relations. We propose seven practice recommendations to improve STEM K‐12 education: (1) design relational classrooms, (2) teach the history of gender inequality and bias, (3) foster collaborative and cooperative classrooms, (4) promote active learning and growth mindset strategies, (5) reframing STEM as inclusive, (6) create near‐peer mentorship programs, and (7) re‐imagine evaluation metrics. To support these practice recommendations, three policy recommendations are posited: (1) increase teacher autonomy, training, and representation, (2) re‐evaluate standardized testing, and (3) reallocate and increase government funding for public schools.