Objective: To examine the effectiveness of motivational interviewing training on improving medical students\u27 knowledge of and confidence in their ability to counsel patients regarding health behavior change. Subjects and Methods: In the spring of 2002, 42 first-year medical students participated in a counseling course on health behavior change. Three small groups focused on learning and practicing motivational interviewing techniques using brief lectures, interactive class activities, student role-plays, and stimulated patients. Students completed an identical precourse and postcourse questionnaire that measured their confidence and knowledge regarding counseling skills in health behavior change. Results: The medical students reported improved confidence in their understanding of motivational interviewing after participation in the course (very confident, 77%) compared with before the course (very confident, 2%). Each of the 8 confidence items were compared before and after the course using a signed rank test. All comparisons indicated a significant improvement (P\u3c.001) in confidence. Regarding knowledge-based questions, students showed significant improvement; 31% of students answered all the questions correctly before the course, and 56% answered all the questions correctly after the course (P=.004). Conclusion: These results show that teaching motivational interviewing techniques to first-year medical students can enhance student confidence in and knowledge of providing counseling to patients regarding health behavior change