We conducted a systematic review of empirical research focused on the experiences of female students in science, technology, engineering, and mathematics (STEM) during middle and high school. Drawing on social identity theory, recent research was synthesized to explore how aspects of the social environment influence STEM identity development. Findings indicate that young women experience challenges to their participation and inclusion when they are in STEM settings. Additionally, we found that perceptions regarding who is part of the ingroup or outgroup of STEM fields can be changed through intervention and educational programs. We conclude with recommendations for theory, research, programs, and policy for STEM identity development among young women, informed by a social identity perspective.