From 2009 to 2019, staff, students, and faculty volunteers from a chiropractic college started Mission Trip America, later re-named Service Trip America (STA), providing monthly free chiropractic services at a hiring hall for day laborers in San Francisco until the 2020 COVID-19 hiatus. We report on volunteers' service-learning experiences. Mixed-methods analysis comprising document review, descriptive report of site visit records, and thematic analysis of semi-structured interviews with 12 student and faculty volunteers. STA conducted 104 visits (8–11 per year) including 2272 patient encounters. Document review revealed an average of 22 patients per visit, with 60% to 85% return patients. On average, 3 student interns and 2 student assistants attended each visit, supervised by a doctor of chiropractic faculty member and the program director. Most commonly, interns treated 8 patients during the 4- to 5-hour visits. Patient concerns included musculoskeletal problems and other health conditions commonly seen at chiropractic offices and teaching clinics. Interns also regularly saw chronic health problems exacerbated by poor living conditions, violence, limited access to health care, low educational attainment, chronic stress, and the extreme biomechanical loading resulting from heavy labor. Interview results yielded 4 themes: learning, attitudes, challenges, and program strengths. Interviewees described opportunities to learn while working with a marginalized population and discussed long-term effects on their postgraduation practice as chiropractors. Patients' physical, mental health, and psychosocial issues illustrated unique circumstances and profound needs of the underserved population being cared for by STA volunteers. Our findings may provide guidance for other community-based chiropractic service-learning programs in marginalized and underserved communities. [ABSTRACT FROM AUTHOR]