ABSTRACT This study tested a conceptual model of factors contributing to students’ interest in science, technology, engineering, and mathematics (STEM) careers. The interrelations among STEM career interest, engagement in physics classes, epistemic cognition in physics, gender, the socioeconomic status (SES), and physics grade of students were investigated. A sample of 8513 high school students participated in the study. Latent-variable structural equation modelling was employed. The results revealed that STEM career interest was significantly related to engagement, epistemic cognition, gender, and SES. However, the prediction pattern was non-uniform across the different STEM domains. Thus, disciplinary differences were observed in the factors that significantly predict students' interest in careers. Mediation analysis revealed that student engagement mediated the relation of epistemic cognition and gender to STEM career interest and physics grade. Epistemic cognition mediated the relationship between SES and STEM career interest. Significant gender and SES-related differences were also observed and are discussed herein.