Infection with human papillomavirus (HPV) has been clearly established as the central cause of cervical cancer. The current phase 3b study is designed to assess the immunogenicity and safety of GlaxoSmithKline Biologicals' HPV vaccine GSK580299 administered according to an alternative dosing schedule as compared to the standard dosing schedule in young female subjects aged 15 - 25 years. The Protocol Posting has been updated in order to comply with the FDA Amendment Act, Sep 2007.