This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. PACTG P1047 is a Phase II, randomized, double-blind, placebo-controlled safety and immunogenicity study of an investigational vaccine, GARDASILTM (a prophylactic Quadrivalent HPV [Types 6, 11, 16, 18] L1 Virus-Like Particle [VLP] vaccine), in HIV-infected children. This vaccine has demonstrated efficacy and the manufacturer has submitted an application for liscensure for use in healthy people aged 9yr to adult has been submitted to the FDA. Studies in immunocompromised people, including those with HIV, have not yet been performed. The primary objectives of this study are to determine the safety, tolerability and immunogenicity of GARDASILTM in HIV-infected children aged 7-12 years. The secondary objectives are to relate the safety and immunogenicity of GARDASILTM to the immune status at the time of vaccination; to further characterize the nature of the immune response; and to determine the response to a fourth (booster) dose of vaccine. The study will enroll 120 children > 7 to < 12 years of age nationally and 13 children locally to be randomized to receive GARDASILTM or vaccine-matched aluminum placebo in a 3:1 ratio. Ninety children will receive GARDASILTM and 30 children will receive placebo, 0.5 mL IM at Entry and at 8 and 24 weeks. Subsequent safety assessments and sample collections will extend until Week 96. Subjects will be unblinded at Week 96. Those who received GARDASILTM will receive an additional dose of GARDASILTM. Those who received placebo will begin a full 3-dose regimen of GARDASILTM. The study design requires that all subjects be enrolled within 12 months of initiating accrual, in order to ensure data entry and clean-up prior to unblinding the first subject at the Week 96 visit.