Peer sexual health education programs are widespread on college campuses, but little research has assessed the effect of these programs on the peer educators. This study employed a repeated measures design to examine changes over the academic quarter in the knowledge, counseling self-efficacy, and sexual behavior of 70 college students enrolled in three different peer educator training programs. Skills necessary for effective sexual health counseling, including knowledge of sexually transmitted diseases and counseling self-efficacy, significantly increased from pre-test to post-test. There were no significant changes in risky sexual behavior, measured by the number of partners and nonuse of barrier methods during penetrative encounters. Participants in a student-taught training program, which prepares enrollees to work in an on-campus resource center, demonstrated the most improved knowledge and counseling self-efficacy. These results suggest that programs training peer educators may improve trainees' knowledge and confidence in their abilities to counsel other students about sexual health. (Contains 2 tables.)