In addition to infant vaccination, the Advisory Committee on Immunization Practices (ACIP) recommends adults at high risk of infection (injection drug users, men who have sex with men, individuals with HIV infection, etc.) be vaccinated against hepatitis B vaccine (HBV). However, the list of high-risk individuals included in the current recommendations is long and includes adults with a variety of health conditions and risk behaviors, which could lead to confusion or challenges in implementation among providers. Estimates from the National Health Interview Survey indicate only 32.9% of adults aged 19-49 and 15.9% of adults 50 years of age or older have received three doses (the required amount to receive optimal levels of seroprotection) of the HepB vaccine. This project will assess several alternative strategies that aim to simplify HepB vaccine recommendations, increase vaccine coverage among adults and reduce the overall rate of new HBV infections. The alternative strategies will be 1) universal vaccination of all adults; 2) targeted vaccination among defined age categories and 3) targeted vaccination among specific geographic regions.