Evaluating the immunogenicity of HIV vaccines is critical to improving vaccine design and development. The adenoviral vector HIV vaccine VRC-HIVADV014-00-VP has shown immunogenicity in early studies and appeared safe and well tolerated at three different doses in a prior dose-escalation vaccine trial in HIV uninfected adults. The DNA HIV vaccine VRC-HIVDNA009-00-VP has shown immunogenicity in multiple clinical trials; in one trial, the DNA vaccine demonstrated a nearly 100% CD4 T-cell response rate. The DNA plasmids in both vaccines code for proteins from HIV subtypes A, B, and C, which together represent 90% of new HIV infections. This study will determine the safety and immune response to the administration of an adenoviral vector HIV vaccine or a DNA HIV vaccine, each followed by an adenoviral vaccine boost, in HIV uninfected adults.