IPV is an FDA licensed drug. No investigational drugs are being used for the purpose of this study. No routine vaccinations are being withheld for the purpose of this study. Those participants randomized to the WHO/EPI schedule will receive their vaccines on a different time schedule than they would usually follow in Puerto Rico. However, both schedules meet the parameters of the Advisory Committee of Immunization Practices (ACIP) 2. Because participants will be followed closely for up to 6 months of life, it is likely that they will receive their vaccinations in a more timely manner than they might if not a part of the study. Parents will be given a unique immunization card showing the schedule their infant will follow; all vaccines administered will be recorded. The card will indicate that they are enrolled in a study and list study staff names and contact telephone numbers.