Adolescents should be enrolled in ethically appropriate and scientifically rigorous HIV biomedical prevention research involving vaccines, pre-exposure prophylaxis, or microbicides. There is general agreement that children should only be enrolled in a clinical trial if the scientific objectives cannot be met either through enrolling adult subjects who can provide informed consent personally or through conducting research using animal models. In addition, the risks to which children are exposed in a clinical trial without the possibility of direct therapeutic benefit must be low. Children also should not be placed at a disadvantage after being enrolled in a clinical trial by, for example, being exposed to an unnecessarily risky intervention or by failing to receive a comparable treatment that would prevent significant morbidity or mortality. In light of this shared framework, we discuss the timing of enrolling adolescents in HIV prevention trials; some general study design considerations that may be necessary for adequate labeling of products for an adolescent indication; the use of data obtained from international studies for licensure applications in the United States; the role of parental permission and adolescent assent to research participation; and the inclusion of pregnant adolescents in HIV biomedical prevention research.