This article characterizes the political ideology of first-year medical students and describes the extent to which their political ideology was associated with attitudes and beliefs related to the care of marginalized patients assessed during their fourth year. Analyses use data from online questionnaires administered to 3,756 medical students from a stratified random sample of forty-nine medical schools in their first and fourth years of study. The primary measure of political ideology was a five-point scale anchored by “very conservative” and “very liberal.” Mixed-effects linear regression was used to test the predictive power of political ideology at year 1 on year 4 outcomes. Among incoming medical students, 47.7% identified as liberal, 33.3% as moderate, and 19.0% as conservative. More conservative ideology was associated at year 4 with greater implicit bias against black and gay individuals, more negative explicit attitudes toward stigmatized groups, lower internal motivation to control racial prejudice, lower levels of trait empathy and empathy toward patients, and lower levels of patient-centered attitudes. Future research is needed to inform and develop interventions to improve care of patients from marginalized groups that are effective for medical students and health care providers across the political spectrum.