Social and behavioral science research is integral to the conduct of HIV vaccine trials, especially because the vaccine targets an infection laden with sensitive human issues. Although social and behavioral sciences have played a larger role in HIV vaccine clinical trials than other vaccine clinical trials to date, this role should be expanded. Fortunately, related publications, conference coverage and research proposals are on the rise; community engagement is receiving more attention during the earlier stages of product development; and collaboration between HIV vaccine scientists and social and behavioral scientists is being fostered. Greater attention to social and behavioral science issues could not only facilitate accrual, but also improve research efficiency and relevance. In this review, gaps in the literature on social and behavioral science issues in HIV vaccine clinical research, including barriers and facilitators to trial participation, enhancing feasibility of trial success, health systems, policy and monitoring social and behavioral issues, are identified and directions are suggested for filling those gaps. Development of a safe, efficacious and acceptable HIV vaccine will be nurtured by addressing the gaps through interdisciplinary collaborations.