Recent clinical trials have demonstrated overwhelming success of biomedical tools to prevent the spread of HIV infection. However, the complex and somewhat disparate results of some of these trials have highlighted the need for effective integration of biomedical and behavioral sciences in the design and implementation of any future intervention trial. Integrating behavioral and biomedical sciences will require appropriate behavioral theories that can be used in the context of biomedical clinical trials and multidisciplinary teams working together from the earliest stages of trial design through to completion. It is also clear that integration of behavioral science will be necessary to implement prevention at the population level and reverse the HIV epidemic.