The objective of this study is to evaluate interventions to increase acceptance of, and follow through with, hepatitis B virus (HBV) immunization among patients attending sexually transmitted disease (STD) clinics in Chicago, IL and Indianapolis, IN. This research will have implications for the design of interventions that may increase HBV vaccine uptake in at-risk groups. The interventions may also be applicable to other STD vaccines as they become available. The first specific aim is to assess the effect of message framing on vaccine acceptance. Prospect theory will be used to guide the development of the message-framing interventions. This theory suggests that positively framed messages (i.e., benefits of getting vaccine) are more effective than negatively framed messages (i.e., dangers of not getting vaccine) in stimulating preventive health behaviors. Research on Prospect Theory and engagement in health behaviors suggests also that the effects may be moderated by other attitudinal factors, including perceived risk of the behavior and degree of involvement in the message. The second aim is to evaluate the effect of provider-based interventions. Prior research suggests that recommendations by health providers are very important in patients' decisions regarding acceptance of healthcare procedures. The third aim is to examine the effect of the interventions on follow-through with the second and third recommended vaccination. During Year 1 of the proposed plan, the message framing interventions will be developed and pilot tested and healthcare providers in Chicago and Indianapolis will be trained in the provider-based interventions. During Years 1-5, 3,344 patients (18 years and older) will be recruited and followed from Chicago and Indianapolis STD clinics during routine medical visits. An audio computer-assisted self-interview (A-CASI) will cover demographics, risk behaviors, and perceived risk associated with vaccination. Subjects then will be randomized to receive a gain-framed, loss-framed, or information only message regarding HBV immunization (also delivered by A-CASI). Upon completion of the message-framing intervention, subjects will be complete additional attitude questions via A-CASI, then will be randomly assigned to one of two provider intervention conditions: 1. vaccine-offered or 2. vaccine-recommended. For both conditions free HBV immunization will be provided by a nurse practitioner. Debriefing interviews will be carried out. Subsequently, postcard reminders will be sent and phone call reminders made for follow-up appointments for those receiving the first and second doses of vaccine. Outcome measures of interest include: (1) acceptance vs. rejection; (2) compliance with two doses vs. one dose only; and (3) completion of immunization vs. two doses only. The relationships of the interventions, socio-demographics, attitudes and behaviors to the outcome measures will be assessed with multiple logistic regression (MLR) and path analysis via structural equation modeling.