This study will use the licensed HPV vaccine, an alternative STI vaccine, as a proxy for an HIV vaccine and thereby identify potential challenges to the inclusion of adolescents in HIV prevention trials. The study will allow for site capacity building in terms of recruiting and retaining an HIV-negative high-risk adolescent cohort, and assessing the acceptability of an STI vaccine to adolescents and their parents or guardians. Correlates of vaccine uptake, refusal, retention and attrition will be determined. In addition, the study will document the incidence of HIV, other sexually transmitted infections (STI's) and pregnancies and circumcisions in this age group. Different methods of assessing understanding in adolescents will be tested, to ensure that informed consent is being achieved. Experiences of privacy and confidentiality issues for adolescents in such research will be explored. Finally, psycho-social correlates of sexual risk and protective behaviour will be examined.