Background: To meet the growing demand for the science, technology, engineering, and mathematics (STEM) workforce and remain competitive in the fields of science and technology over the next decade, the United States is expected to need more than 1 million additional STEM professionals. This would require an annual increase of 34% in undergraduate STEM degrees over the next decade to meet the projected need. Purpose: This study examined the relationship between Advanced Placement (AP) STEM course-taking in high school and selection of college STEM majors and whether the relationship differs by gender and race/ethnicity. Design/Method: For controlling student and school factors, a binary logistic regression model with the clustered standard error was utilized to determine the relationship between AP STEM course-taking and STEM major selection. Multinomial logistic regression was conducted to further understand how AP STEM course-taking was associated with engineering major selection. The analysis included a series of interaction effects tests, examining the variation of gender and racial/ethnic differences in STEM and, more specifically, engineering major selection as a function of AP STEM course-taking. Results: Findings indicate gender and AP STEM course exposure are significant in predicting STEM major selection. Interaction effects test results further show that the relationship between AP STEM course-taking and STEM major selection varies significantly by gender. A similar pattern is found in the relationship between AP STEM course-taking and engineering major selection. Conclusion: This study provides much-needed empirical evidence to understand the relationships between AP STEM courses course-taking in high school and the selection of college STEM majors and how such relationships vary by race/ethnicity and gender. Additional research is encouraged to inform future educators and policymakers in promoting equity for students in pursuing paths to STEM and, more specifically, engineering-related careers.