This study uses data from the Youth Risk Behavior Survey (YRBS) conducted in Philadelphia to estimate the prevalence of youth homelessness and risk for problems in the areas of victimization, binge drinking, serious substance use, and mental health. The YRBS is an anonymous, self-report survey that produces population-representative estimates for all Philadelphia high school students. About 16.3% of all youths reported having experienced homelessness at some point in their lives, and 11.7% reported current or recent homelessness. Homelessness, especially current or recent homelessness, was associated with higher levels of victimization and higher likelihood of experiencing a behavioral health problem. Follow-up tests generally confirm the presence of a risk gradient for each individual outcome wherein never-homeless students show the lowest level of risk, students who had been homeless only in the past an intermediate level of risk, and currently or recently homeless students the highest level of risk. Results are consistent with the view that homelessness represents a period of crisis or acute risk that challenges positive adaptation, often in the context of chronic risk.