Purpose <p>Despite efforts to implement disabilities curriculum into the four years of undergraduate medical education (UME), the absence of a mandated, comprehensive, longitudinal curriculum likely contributes to health disparities experienced by people with disabilities (PWD). We examine the impact of the first mandated four-year medical school disabilities curriculum on five cohorts of allopathic medical students’ knowledge, confidence, and attitudes regarding care for PWD.</p> Methods <p>During academic years (AY) 2020–2021 through 2023–2024, seven mandatory disability-specific interventions were interspersed throughout the UME program. Since curricula were developed over the four-year period, it was not possible for every student to experience all seven curricular interventions; collective survey respondents per session ranged from 58 to 899. Session content included: apparent and non-apparent disabilities; ableism, bias, and stigma; functional limitations, barriers, and accommodations; impact of bias on physical and sexual health; and supporting the transition of PWD from pediatric to adult care. Students were assessed objectively and subjectively at four timepoints and completed a reflective essay. The Wilcoxon matched-pairs signed-ranks test was used to assess differences between pre- and post-session survey results. In AY 2023–2024, a validated attitudes survey was administered before and after a fourth-year intervention; students demonstrated statistically significant improvement in several areas. Optional eighth (<i>n</i> = 57) and ninth sessions (<i>n</i> = 8) were piloted to practice hands-on safe patient-transfer protocols and hone communication with patients with intellectual and developmental disabilities, respectively. Qualitative inductive content analysis was used to evaluate the essay question.</p> Results <p>Five cohorts (<i>n</i> = 899) demonstrated statistically significant increases in knowledge and confidence in various disabilities-related areas. Essays from two cohorts (<i>n</i> = 423) expressed commitment to addressing healthcare disparities and unconscious bias, promoting effective communication, and providing empathetic care to PWD. Validated student attitude surveys of one cohort (<i>n</i> = 58) demonstrated significant increases in recognizing the quality of life of PWD, comfort around a person who is blind or deaf, and comfort performing a physical exam on a patient who uses a wheelchair.</p> Conclusions <p>Objectively and subjectively, medical students who engaged in curricular sessions reported increased knowledge and comfort caring for PWD, and many demonstrated statistically significant improvements in their perceived confidence in supporting PWD. This is the first mandated four-year UME disabilities curriculum to be published.</p>