Professionalism is a core competency of medical training that requires students to develop the skills of providing and receiving feedback. Our study evaluated the effectiveness of delivering feedback in a group setting compared with an individual setting. The first-year class of Mayo medical students (n = 49) enrolled in gross anatomy (in dissection teams), completed weekly anonymous evaluations of themselves and their teammates regarding seven aspects of professionalism (altruism, compassion, respect, honesty/integrity, responsibility, commitment to excellence, and self-reflection). Professionalism scores from these surveys were calculated using a six-point Likert scale. Students were also asked to comment on strengths and possible areas for improvement on each peer. At the midpoint of the course, peer comments and professionalism scores were shared with students in debriefing sessions either individually or with their team. Analysis of preintervention and postintervention professionalism scores indicated that the students receiving feedback in a one-on-one setting (student and instructor) were more likely to demonstrate higher scores on subsequent evaluations as compared with those students receiving feedback in a group setting (all team members and one instructor). Our findings suggest that providing feedback to first-year medical students on an individual basis is the best way to improve professional attitudes and behaviors. (Contains 4 tables.)