Adolescents worldwide are at high risk for HIV, which makes them essential candidates for HIV vaccine trials. However, enrollment of adolescents into such trials has implications for trial sites. Adolescents are considered vulnerable subjects and require proxy consent in addition to their assent, which brings issues of confidentiality and access into play. HIV vaccine trial sites often do not have experience recruiting and retaining adolescents, and creating youth-friendly environments that are comfortable for guardians. This includes development of education materials that target both youth and their parents. Because these trials are of minimal individual benefit, sites will likely need to provide service in the form of health care and supportive structures to adolescents. Finally, a number of trial design options exist, and researchers will need to balance the risks and benefits of each, as for all issues surrounding the involvement of adolescents in HIV vaccine trials.