Immunogenicity and Safety Study of GSK Biologicals' Meningococcal Vaccine GSK 134612 Versus Menactra® in Healthy Adolescents/Adults

Inclusion Criteria: All subjects must satisfy ALL of the following criteria at study entry: * Subjects whom the investigator believes that they and/or their parent(s)/Legally Acceptable Representative(s) can and will comply with the requirements of the protocol. * A male or female between, and including, 10 and 25 years of age at the time of the vaccination. * Written informed consent obtained from the subject/from the parent or Legally Acceptable Representative(s) of the subject. Assent will be obtained from subjects who are still legally minors in line with local rules and regulations. * Healthy subjects as established by medical history and clinical examination before entering into the study. * Previously completed routine childhood vaccinations to the best of subject's/Legally Acceptable Representative(s)'s knowledge. * 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 for 2 months after vaccination. Exclusion Criteria: The following criteria should be checked at the time of study entry. If ANY exclusion criterion applies, the subject must not be included in the study: * Use of any investigational or non-registered product other than the study vaccine(s) within 30 days preceding the dose of study vaccine, or planned use during the study period. * Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to vaccination. (For corticosteroids, this will mean prednisone \<10 mg/day, or equivalent, is allowed. Inhaled and topical steroids are allowed.) * Planned administration/administration of a vaccine not foreseen by the study protocol within one month of the dose of vaccine, with the exception of any licensed inactivated influenza vaccine. * Previous vaccination with meningococcal polysaccharide or conjugate vaccine. * Previous vaccination with vaccine components within the last month. * History of meningococcal disease. * Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus infection, based on medical history and physical examination. * A family history of congenital or hereditary immunodeficiency, until the immune competence of the potential vaccine recipient is demonstrated. * History of allergic reactions or disease likely to be exacerbated by any component of either vaccine, or by dry natural rubber latex. * History of any neurologic disorders, including Guillain-Barré Syndrome. * Major congenital defects or serious chronic illness. * Acute disease at the time of enrollment. * Administration of immunoglobulins and/or any blood products within the three months preceding the dose of study vaccine or planned administration during the study period. * Pregnant or lactating female. * History of chronic alcohol consumption and/or drug abuse. * Female planning to become pregnant or planning to discontinue contraceptive precautions. * Bleeding disorders, such as thrombocytopenia, or subjects on anti-coagulant therapy. * Child in care. * 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.