A peer mentoring program was added to an introductory chemistry course at a large university. The introductory chemistry course prepares students with little or no previous chemistry background to enter the mainstream general chemistry sequence and is part lecture and part small-group problem-solving. Faculty instructors are responsible for the lecture while peer mentors handle the group problem-solving portion. Peer mentors, recruited from previous introductory chemistry course, are chosen for their knowledge of the material and their helpfulness in group activities. While a number of studies on peer mentoring have reported the benefits to the mentored students, the present study looks at the benefits to the mentors. Grade enhancement in the main-stream general chemistry sequence, withdrawal rates, and number of additional chemistry courses taken by the mentors have been compared to under-prepared students who took the introductory chemistry course but did not serve as mentors and well-prepared students who did not need the introductory chemistry course. Our results show that mentors earned higher grades, withdrew from chemistry courses at a lower rate, and took more courses in chemistry than their counterparts. The enhanced achievement and retention of the mentors in chemistry suggests that programs that encourage under-prepared students to mentor are worthwhile endeavors. (Contains 4 tables and 2 figures.)