The investigators seek to provide immunization for individuals who are at high risk of contracting hepatitis B virus (HBV) infection because of their illicit drug use. The investigators will be using the syringe exchange programs (SEPs) in Hartford and Bridgeport, CT and Chicago, IL to contact high risk individuals and refer them for vaccination. The primary purpose of the study is to compare the standard schedule of hepatitis B vaccination at 0, 1, and 6 months to an accelerated schedule of vaccination at 0, 1, and 2 months. The investigators hypothesize that the accelerated scheduling will result in improved completion rates without significant loss in vaccine efficacy.

Inclusion Criteria:

• Demonstrate evidence of recent injection drug use (injection stigmata),
• 18 years of age or older,
• Screened for and found susceptible to HBV
• Able to provide informed consent.

Exclusion Criteria:

• Evidence of intoxication that prevented provision of informed consent.