The present study focuses on the results of a four-year study that examined a Harmony Public School (HPS) high school students' STEM major selection patterns. We utilize 626 12th grade students who were common participants in each year of the 4-year study. We used quantitative method for the question 1 and 2 and a mainly qualitative focus for the question 3. Descriptive statistics for the first question revealed that HPS students had higher rates in STEM career interest in all categories including gender and race/ethnicity throughout each of the four years of the study. For the second research question, we found that male students with higher science self-efficacy scores and less STEM club participation have a statistically significant effect on students' STEM major choice. For the third question, students indicated that their parents and teachers, and courses taken in high school were their top three factors that influenced their STEM career selection.