The physician-scientist workforce struggles to attract racial and ethnic groups historically underrepresented in medicine (URiM), including individuals who are Black, Hispanic, American Indian or Alaskan Native, Native Hawaiian, and other Pacific Islander. Because the national research agenda is often set by those conducting scientific studies, increasing the diversity of the physician-scientist workforce has the potential to bring greater focus on issues that disproportionately affect racial and ethnic minorities. Notably, racial and ethnic minority physician-scientists are more likely to pursue scholarship related to racial/ethnic health inequities. Prior work has demonstrated that research career intentions evolve significantly during medical school and that research career intentions at graduation are associated with tangible downstream measures of research success, including subsequent receipt of NIH funding. Our preliminary data show marked disparities between URiM and non-URiM students in research career intentions during medical school. We propose a 5-year, longitudinal, mixed-methods study to identify trajectories (i.e., evolution over time) of research career intentions, and determinants thereof, in 400 URiM (based on race and ethnicity) students matriculating into MD programs and to compare these with trajectories and determinants in 200 non-URiM students. We will examine experiences at the individual level, such as quality of mentorship and experiences of discrimination, as well as experiences at the institutional level, such as URiM representation in the school's leadership. The aims are to: 1) identify trajectories of research career intentions among URiM students throughout medical school training and make comparisons with trajectories in non-URiM students; 2) identify student- and institutional-level predictors of research career intention trajectories in URiM students and make comparisons with predictors in non-URiM students; 3) use qualitative methods to characterize nuanced, lived experiences related to evolution of research career intentions. Quantitative and qualitative data will be integrated using a convergent approach at the levels of study design, analysis, interpretation, and reporting of results. This study is significant because it will identify potentially influential timepoints and predictors of change in research career intention among URiM MD students that can be used to increase the racial and ethnic diversity of the physician-scientist workforce. This diversity can help mitigate health disparities by broadening the national research agenda and increasing research participation by underrepresented populations. Our assessment of the roles of racism and discrimination in shaping research career intentions is innovative. The impact of our findings will be enhanced by our strong partnerships with national organizations, including medical education leaders at the National Academies of Sciences, Engineering, and Medicin...