ImportanceDiversity in the physician workforce improves patient care and decreases health disparities. Recent calls for social justice have highlighted the importance of medical school commitment to diversity and social justice, and newly established medical schools are uniquely positioned to actively fulfill the social mission of medicine.ObjectiveTo identify diversity language in the mission statements of all medical schools accredited since 2000 and to determine whether the presence of diversity language was associated with increased diversity in the student body.Design, Setting, and ParticipantsCross-sectional study of public websites conducted between January 6, 2023, and March 31, 2023. Qualitative content analysis of mission statements was conducted using a deductive approach. Eligible schools were identified from the 2021-2022 Medical School Admission Requirements and American Medical Colleges and American Association of Colleges of Osteopathic Medicine websites. Each school’s publicly available website was also reviewed for its mission and student body demographics. All United States allopathic and osteopathic medical schools that have been accredited and have enrolled students since 2000.ExposureContent analysis of medical school mission statements.Main Outcomes and MeasuresPrevalence of diversity language in medical school mission statements and its association with student body racial diversity. Data were analyzed in 5-year groupings: 2001 to 2005, 2006 to 2010, 2011 to 2015, and 2016 to 2020).ResultsAmong the 60 new medical schools (33 [55%] allopathic and 27 [45%] osteopathic; 6927 total students), 33 (55%) incorporated diversity language into their mission statements. In 2022, American Indian or Alaska Native individuals accounted for 0.26% of students (n = 18), Black or African American students constituted 5% (n = 368), and Hispanic or Latinx individuals made up 12% (n = 840). The percentage of schools with diversity language in their mission statements did not change significantly in schools accredited across time frames (60% in 2001: mean [SE], 0.60 [0.24] vs 50% in 2020: mean [SE], 0.50 [0.11]). The percentage of White students decreased significantly over the time period (26% vs 15% students in 2001-2005 and 2016-2020, respectively; P < .001). No significant differences were observed in student body racial or ethnic composition between schools with mission statements that included diversity language and those without.Conclusions and RelevanceIn this cross-sectional study of US medical schools accredited since 2000, diversity language was present in approximately half of the schools’ mission statements and was not associated with student body diversity. Future studies are needed to identify the barriers to increasing diversity in all medical schools.