This study is to evaluate the steady-state pharmacokinetics (PK) and confirm the dose of the elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/COBI/FTC/TDF) single tablet regimen (STR) in HIV-1 infected, antiretroviral (ARV) treatment-naive adolescents. Safety, tolerability, and efficacy will also be evaluated through Week 48.