IMPORTANCE National organizations recommend that medical schools train students in the social determinants of health. OBJECTIVE To develop and evaluate a longitudinal health equity curriculum that was integrated into third-year clinical clerkships and provided experiential learning in partnership with community organizations. DESIGN, SETTING, AND PARTICIPANTS This longitudinal cohort study was conducted from June 2017 to October 2020 to evaluate the association of the curriculum with medical students' selfreported knowledge of social determinants of health and confidence working with underserved populations. Students from 1 large medical school in the southeastern US were included. Students in the class of 2019 and class of 2020 were surveyed at baseline (before the start of their third year), end of the third year, and graduation. The class of 2018 (No curriculum) was surveyed at graduation to serve as a control. Data analysis was conducted from June to September 2020. EXPOSURES The curriculum began with a health equity simulation followed by a series of modules. The class of 2019 participated in the simulation and piloted the initial 3 modules (pilot), and the class of 2020 participated in the simulation and the full 9 modules (full). MAIN OUTCOMES AND MEASURES A linear mixed-effects model was used to evaluate the change in the self-reported knowledge and confidence scores over time (potential scores ranged from 0 to 32, with higher scores indicating higher self-reported knowledge and confidence working with underserved populations). In secondary analyses, a Kruskal-Wallis test was conducted to compare graduation scores between the no, pilot, and full curriculum classes. RESULTS A total of 314 students (160 women [51.0%], 205 [65.3%] non-Hispanic White participants) completed at least 1 survey, including 125 students in the pilot, 121 in the full, and 68 in the no curriculum classes. One hundred forty-one students (44.9%) were interested in primary care. Total self-reported knowledge and confidence scores increased between baseline and end of clerkship (15.4 vs 23.7, P = .001) and baseline and graduation (15.4 vs 23.7, P = .001) for the pilot and full curriculum classes. Total scores at graduation were higher for the pilot curriculum (median, 24.0; interquartile range [IQR], 21.0-27.0; P = .001) and full curriculum classes (median, 23.0; IQR, 20.0-26.0; P = .01) compared with the no curriculum class (median, 20.5; IQR, 16.25-24.0). (continued) Key Points Question Is a longitudinal health equity curriculum associated with improved self-reported knowledge of the social determinants of health and confidence with working with underserved populations among US medical students? Findings In this cohort study of 314 students, self-reported knowledge and confidence scores significantly increased over time for participants in both the pilot and full curriculum classes. Compared with students not exposed to the curriculum, those in the pilot and the full curriculum classes had significantly higher scores at graduation. Me...