Risks associated with HIV are well documented in research literature. Although a great deal has been written about high-risk sex, little research has been conducted to examine how young men who have sex with men (YMSM) perceive and define high-risk sexual behavior. In this study, we compare the "professional" and "folk" models of HIV risk based on YMSM's understanding of high-risk sex and where and how they gathered their understanding of HIV risk behaviors. The findings reported here emerged from the quantitative and qualitative interviews from the Healthy Young Men's Study, a longitudinal study examining risk and protective factors for substance use and sexual risk among an ethnically diverse sample of YMSM. Findings are discussed in relation to framing how service providers and others can increase YMSM's knowledge of sexual behavior and help them build solid foundations of sexual health education to protect them from sexually transmitted infections and HIV.