Federal policy in the United States has urged high schools to expand offerings in career and technical education (CTE) coursework to address persistent gender inequities in science, technology, engineering, mathematics, and medical (STEMM) fields. Unfortunately, gender composition in engineering and health sciences CTE enrollment is highly imbalanced and reflects postsecondary and labor market trends. Using data from the High School Longitudinal Study of 2009, we use decomposition techniques to examine which student, family, and school factors explain gender-imbalanced enrollment in STEMM-focused CTE courses. The results indicate student occupational expectations were the largest contributor to gender gaps across content areas. [This paper will be published in "Educational Policy."]