Increases in compassionate behavior improve patient outcomes and reduce burnout among healthcare professionals. We predicted that selecting and performing service-learning projects by teams of prospective medical students in a Medical Humanities course would foster students’ compassion by raising their reflective capacity, empathy, and unconscious bias mitigation. In class, we discussed difficulties in communication and implicit bias. In this observational study, teams wrote individual and team critical reflections on these class discussions and their service-learning experiences, and we analyzed these reflections for dissonance, self-examination, bias mitigation, dissonance reconciliation, and compassionate behavior. Thirty-two students (53% female) completed the Reflective Practice Questionnaire and the Jefferson Scale of Empathy before the course in August 2019 and after it in December 2019. In December, students were surveyed concerning their attitudes toward team service-learning projects and unconscious bias. The students reported changes in their behavior to mitigate biases and become more compassionate, and their reflective capacity and empathy grew in association with discussions and team service-learning experiences in the course. Virtually all students agreed with the statement “Unconscious bias might affect some of my clinical decisions or behaviors as a healthcare professional,” and they worked to control such biases in interactions with the people they were serving.