The purpose of this study was to investigate the association between unrealistic optimism (UO) and risky sexual behavior (RSB) and related consequences in a college student sample. Participants believed they had significantly lower "personal" risk of engagement in alcohol-related sexual activity, unintended pregnancy, and STIs than the average college student ("ps" < 0.01). Compared to national data, participants significantly underestimated likelihood of HPV and sexual engagement with four or more partners in the next year ("ps" < 0.01). Findings support evidence of UO relating to RSB-related consequences, indicating need for improvements in sexual health education and intervention.