It is estimated that 10.3 million people aged 15–24 are living with HIV infection/AIDS worldwide, with 7000 new infections occurring each day. Many of these infections occur during the adolescent years. These rates of infection make adolescents an important target for research in primary prevention. Currently, preparations are under way by the National Institutes of Health–supported HIV networks—the Adolescent Trials Network, the Pediatric AIDS Clinical Trials Group, and the HIV Vaccines Trials Network—for phase 1/2 HIV vaccine trials involving adolescents in the United States. Identifying the challenges to conducting HIV vaccine trials with this population is a crucial component of these preparations. Challenges to HIV vaccine trials with adolescents were identified by reviewing previous vaccine research for adolescents and HIV infection in adolescents and speaking with experts in HIV/AIDS and adolescent medicine. Adolescents (typically those younger than 18 years of age) are minors and fall under ethical and regulatory safeguards for their participation in clinical research including parental permission. Adolescents may not appropriately perceive personal risk, posing challenges for informed consent as well as prevention counseling during a trial. Safety and immunogenicity studies of adolescents are likely to be required by the US Food and Drug Administration before vaccine approval for this population. Early identification and subsequent follow-up of high-risk adolescents are problematic. Vaccine-induced seropositivity may present potential barriers to military service, employment, marriage, and acquiring health insurance. The age at optimal immunization, particularly for girls in some countries, may be during preadolescence. The successful completion of HIV vaccine trials with adolescents must address these challenges both in the United States and internationally. This report addresses relevant background information, identifies the issues surrounding HIV vaccine trials with adolescents, discusses what progress has been made, and addresses plans and implications for the implementation of these trials.