This study investigates undergraduate STEM persistence through two-factor theory. Using nationally representative data and multinomial regression, we conceptualize known determinants of persistence as hygiene and motivator factors to test the persistence outcomes among college students who majored in STEM: earning a STEM degree, non-STEM degree, and degree non-completion. We propose that hygiene factors provide a baseline means of persistence in higher education, whereas the motivator factors improve the probability of student persistence in STEM majors. Our findings demonstrated that motivator factors improve the persistence model when added to hygiene factors. Hygiene factors were generally associated with STEM persistence by staying in college, while motivator factors mostly predicted persistence by remaining in the STEM major. Given the importance of motivator factors, we also tested the differential relationship between motivator factors and student persistence in STEM majors by gender and race/ethnicity due to underrepresentation in STEM fields.