Large introductory science, technology, engineering, and mathematics (STEM) courses historically have high failure rates, and failing such courses often leads students to change majors or even drop out of college. Institutional change models such as the Learning Assistant (LA) model can influence this trend by changing institutional norms. In collaboration with faculty who teach large-enrollment introductory courses, undergraduate learning assistants (LAs) use research-based instructional strategies designed to encourage active student engagement and elicit student thinking. In this study, we use logistic regression to investigate the relationship between exposure to LA support in these large introductory courses generally and failure rates in Physics I and II specifically at University of Colorado Boulder. We find that exposure to LA support is associated with lower failure rates in introductory physics courses and that the magnitude of the relationship is larger for female and first-generation college students.