There is a national shortfall of women and minorities in the science, technology, engineering, and math (STEM) fields. Thus, it is imperative to understand the factors that impact students' decisions to pursue a STEM field of study. The purpose of this quantitative study was to assess the impact of science self-efficacy beliefs of female high school seniors on intent to major in a STEM field. The research was framed by both the Science Self-Efficacy Theory and the Social Cognitive Career Theory. This study used The Science Self-Efficacy and Sources Survey to measure factors impacting girls' science self-efficacy. High school seniors from an urban high school received the survey, and due to COVID-19 virtual learning constraints, only 139 of the 408 students completed the study. Three research questions were analyzed using an ANOVA test, and one research question was assessed using multiple linear regression. This study revealed the following results: there is a statistically significant relationship between science self-efficacy and STEM major choice; there is a statistically significant relationship between science self-efficacy and student gender, with male students having a higher science self-efficacy than their female peers; the proximal contextual factors mastery experiences, vicarious learning, and physiological effect predict science self-efficacy, with mastery experiences being the most impactful; and, enrollment in an academic specialty program predicts science self-efficacy. The data findings support the conclusion that students' academic self-efficacy impacts college major choice and understanding the factors that increase female students' science self-efficacy may improve interest and participation in STEM fields of study. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]