The purpose of this study was to evaluate the safety, efficacy, and immunogenicity of V503 in comparison to GARDASIL. The primary hypotheses tested in the study were 1) V503 administered to 16- to 26-year-old adolescents and young women is generally well-tolerated, 2) V503 reduces combined incidence of Human Papillomavirus (HPV) Type 31/33/45/52/58-related disease compared with GARDASIL, and 3) V503 induces non-inferior geometric mean titers for HPV Type 6/11/16/18 antibodies compared with GARDASIL.