Black and Latino young men who have sex with men (YMSM) are disproportionately impacted by HIV infection; however, the reason for this disparity is unclear. To identify possible causes of the higher rates of HIV infection in this population, data from studies of HIV infection and risk-related behaviors among black and Latino YMSM were used to evaluate a series of hypotheses adapted from Millett et al's literature review that might explain the disparity. High rates of HIV infection might be attributable to unrecognized HIV infection, social/sexual networks, and a history of childhood sexual abuse; however, they were not attributable to risk-related behaviors. More research is needed to understand the risk factors for HIV infection and how to address them in HIV prevention interventions.