Traditionally underserved students (TUSs), including Black, Latinx, American Native, and low-socioeconomic (SES) students, have higher rates of departure from STEM undergraduate programs than their more privileged peers. These higher departure rates are associated with TUSs' lower performance in STEM gatekeeper courses compared to non-STEM courses through their sophomore year. Flipped models of instruction when used in gatekeeper chemistry courses are broadly shown to improve student course performance (higher course grades; reduced W/D/F rates). However, there is no clear evidence that flipped models specifically improve course performance for TUSs. This study's objective was to determine the impact of a flipped model on students' course performance in General Chemistry I on the basis of their race/ethnicity and SES. Using a nonparallel quasi-experimental design, student performance by race/ethnicity and SES in the flipped model course was compared to that of students in the traditional course. Results show TUSs were significantly more likely to have higher course grades in the flipped model course as compared to the traditional course. Further, the performance gap was closed between Black and Latinx students and their White/Asian peers in the flipped model. However, a performance gap between low-SES and middle- to high-SES students emerged in the flipped model. The W/D/F rate was decreased in the flipped model for all student groups. Therefore, although flipped models are not a panacea, they can be one critical support strategy used in freshman and sophomore chemistry gatekeeper courses to mitigate TUSs' departure from STEM undergraduate programs.