Human Papillomavirus (HPV) infection has been established as a necessary cause of cervical cancer. GlaxoSmithKline (GSK) Biologicals has developed an HPV vaccine (580299) which targets the 2 most common oncogenic HPV types (HPV-16 and HPV-18), found in approximately 70% of all cervical cancers. In previous trials this vaccine has been found to be efficacious in the prevention of incident and persistent HPV-16/18 infections and associated cytological abnormalities and cervical dysplasia. In this partially-blind study, GSK Biologicals will evaluate the safety and immunogenicity of the HPV vaccine using an alternative schedule and an alternative dosing when administered in healthy young females aged 9 to 25 years, as compared to the standard HPV vaccine. The Protocol Posting has been updated in order to comply with the FDA Amendment Act, Sep 2007. The protocol posting has been updated following a protocol amendment.