The worldwide HIV/AIDS epidemic may only be controlled through development of a safe and effective vaccine that will prevent HIV infection. DNA vaccines are inexpensive to construct, readily produced in large quantities, and stable for long periods of time. This study will evaluate the safety and immunogenicity of an experimental multiclade HIV vaccine, VRC-HIVDNA016-00-VP, followed by a similarly structured adenovirus-vectored vaccine boost, VRC-HIVADV014-00-VP, in HIV uninfected adults. The DNA plasmids in both the vaccines code for proteins from HIV subtypes A, B, and C, which together represent 90% of new HIV infections in the world. The study's primary objective is to investigate the ability of a 6-plasmid DNA prime followed by a rAd5 boost to elicit HIV-specific cellular immune responses at mucosal surfaces.