Immunogenicity and Safety Study of GlaxoSmithKline Biologicals' Human Papillomavirus (HPV) Vaccine (GSK-580299) and Merck's Gardasil Vaccine When Administered According to Alternative 2-dose Schedules in 9-14 Year Old Females

Inclusion Criteria:

* Subjects who the investigator believes can and will comply with the requirements of the protocol and subjects who the investigator believes their parent(s)/Legally Acceptable Representative(s) (LAR\[s\]) can and will comply with the requirements of the protocol.
* A female between, and including, 9 and 14 years of age at the time of the first vaccination.
* Written informed consent obtained from the parent(s)/LAR(s) of the subject prior to enrolment in the study. In addition, if capable, the subject should sign and personally date a written informed assent.
* Healthy subjects as established by medical history and clinical examination before entering into the study.
* Female subjects of non-childbearing potential may be enrolled in the study.
* Female subjects of childbearing potential may be enrolled in the study, if the subject:

  * has practiced adequate contraception for 30 days prior to vaccination, and
  * has a negative pregnancy test on the day of vaccination, and
  * has agreed to continue adequate contraception during the entire treatment period and for two months after completion of the vaccination series.

Exclusion Criteria:

* Pregnant or breastfeeding.
* A woman planning to become pregnant, likely to become pregnant (as determined by the investigator) or planning to discontinue contraceptive precautions during the vaccination phase of the study, i.e. up to two months after the last vaccine dose.
* Previous vaccination against HPV or planned administration of another HPV vaccine during the study other than those foreseen in the protocol.
* Child in care.
* Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine within 30 days preceding the first dose of study vaccine, or planned use during the study period (up to Month 36).
* Chronic administration of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose.
* History of allergic disease, suspected allergy or reactions likely to be exacerbated by any component of the study vaccines.
* Cancer or autoimmune disease under treatment.
* Planned administration/administration of a vaccine not foreseen by the study protocol within 30 days before each dose of vaccine. Administration of routine meningococcal, hepatitis B, hepatitis A, inactivated influenza, diphtheria/tetanus and/or diphtheria/tetanus-containing vaccine up to 8 days before each dose of study vaccine is allowed. Enrolment will be deferred until the subject is outside of specified window.
* Concurrently participating in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product (pharmaceutical product or device).
* Previous administration of vaccine components.
* Administration of immunoglobulins and/or any blood products within the three months preceding the first dose of study vaccine or planned administration during the study period.
* Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination.
* Family history of congenital or hereditary immunodeficiency.
* Major congenital defects or serious chronic illness.
* Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by physical examination or laboratory screening tests, which in the opinion of the investigator precludes administration of the study vaccine.
* Acute disease and/or fever at the time of enrolment.
* Drug and/or alcohol abuse.