Despite their high performance in STEM disciplines and earning top grades in math and science classes, many academically talented girls often leave STEM majors or shy away from careers in STEM. Understanding why bright and talented girls leave STEM majors requires an in-depth understanding of the factors that predict their success and retention in STEM. This study, conducted in Post-Soviet Kazakhstan, a country with a strong emphasis on the nation's talented students and STEM-focused education, provides evidence on the underlying reasons for this puzzling phenomenon. The findings from the study provide supportive evidence of the presence of individual and environmental (distal and proximal) factors facilitating and impeding talented girls' STEM progression and retention, as proposed by SCCT theory.