Several key factors have emerged from the literature contributing to the explanation of STEM participation (or lack of), including mathematics mindset, mathematics anxiety, mathematics identity, and mathematics self-efficacy. Despite the research on the relations of these variables to career interest, few studies have integrated them and examined their intertwined relations in one model. The purpose of this study was to use a structural equation modeling approach to answer the central question: To what extent are the factors of mathematics mindset, mathematics anxiety, mathematics identity, and mathematics self-efficacy related to each other and a STEM career choice? The results highlight a key finding that mathematics identity serves as a full mediator between mathematics mindset and STEM career interest as well as between mathematics anxiety and STEM career interest.