The present study provides an experimental demonstration of the influence of induced social comparison on health cognitions. It was predicted that participant risk status and target risk status would interact to produce differences in behavioral willingness (BW) and perceived vulnerability (PV) to a sexually transmitted disease. It was also predicted that social comparison with high vs. low-risk targets would affect behavioral intentions (BI) less than BW, and that interactions between participant and target risk will be stronger among participants who are high in social comparison tendencies than those who are low in social comparison. Participants who reported that they were not married, had engaged in unprotected sex, and had never been diagnosed with an STD were recruited to participate in the study. Each participant was randomly assigned to hear a tape depicting a high or low-risk same-sex comparison target who reported that he or she had tested positive for herpes. Participants then completed a questionnaire that assessed BW, BI, and PV related to unprotected sex. As predicted, high-risk participants who heard from a high-risk comparison target reported higher PV to STDs and lower BW than did high-risk participants who heard from a low-risk target. In addition, low-risk participants who listened to the low-risk comparison target were more likely to report higher PV than those who listened to the high-risk tape. The predicted moderation of these effects by individual differences in social comparison was also found, i.e., the participant risk by target risk interactions were strongest among those who frequently engage in social comparison. Furthermore, willingness, but not intentions, varied significantly as a function of condition, providing further support for the hypothesis that willingness and intentions are distinct constructs.