This two-stage study evaluates the immunogenicity, safety, and tolerability of the administration of VAQTA™ (Hepatitis A Vaccine, Inactivated) concomitantly with PedvaxHIB™ (Haemophilus B Conjugate Vaccine [Meningococcal Protein Conjugate]) and Infanrix™ (Diphtheria and Tetanus Toxoids and Acellular Pertussis Vaccine Adsorbed, GlaxoSmithKline) versus the administration of VAQTA™ in healthy children 15 months of age at study entry.