Many science, technology, engineering, and math degrees require passing an introductory physics course. Physics courses often have high failure rates that disproportionately harm students who are historically and continually marginalized by racism, sexism, and classism. We examined the associations between learning assistant (LA) supported courses and equity in nonpassing grades [i.e., drop, fail, or withdrawal (DFW)] in introductory physics courses. The data used in the study came from 2312 students in 41 sections of introductory physics courses at a regional Hispanic serving institution. We developed hierarchical generalized linear models of student DFW rates that accounted for gender, race, first-generation status, and LA-supported instruction. We used a quantitative critical race theory (QuantCrit) perspective focused on the role of hegemonic power structures in perpetuating inequitable student outcomes. Our QuantCrit perspective informed our research questions, methods, and interpretations of findings. The models associated LAs with overall decreases in DFW rates and larger decreases in DFW rates for Black, Indigenous, and people of color than their White peers. While the inequities in DFW rates were lower in LA-supported courses, they were still present.