Objective: Homeless people have disproportionately high rates of viral hepatitis. The Gelberg-Andersen Behavioral Model for Vulnerable Populations (predisposing, enabling, and need variables) was expanded to predict prevalence and awareness of hepatitis B (HBV) or hepatitis C (HCV) infection, as well as health services utilization (HSU) among homeless adults using structural equation modeling. Design: A population-based sample of 534 homeless adults in Los Angeles’ “Skid Row” was interviewed and tested for HBV and HCV. Main Outcome Measures: Main outcome measures included HBV/HCV seropositivity, awareness of seropositivity, and HSU in the previous 12 months. Results: Seropositivity (43%), usually unknown (72% of seropositives), was predicted by injection drug use, alcohol use, older age, and risky sexual behavior. No regular source of care, risky sexual behavior, less case management, and greater age predicted not knowing one’s positive status. Health insurance, younger age, alcohol use, perceived bad health and more medical conditions predicted emergency room (ER) use; ER use was less likely among seropositives. Hospitalizations were predicted by more medical conditions and greater percentage of life homeless and were less frequent among African Americans and males. Ambulatory visits were predicted by a regular source of care, case management, more education and perceived bad health; they were less likely among seropositives. Conclusion: The Gelberg-Andersen Behavioral Model provided a useful guide for predicting HBV/HCV positivity as well as HSU in homeless adults. Most hepatitis-positives did not know their status and used health services less often than other homeless adults. More aggressive detection of hepatitis B and C among homeless adults is needed.