Puerto Rico will be the study site for this randomized clinical trial. Healthy infants will be identified at birth in a hospital-system, enrolled within 4 weeks of birth, and randomized into one of two arms: United States of America (U.S.A.) schedule (8, 16, 24 weeks/2, 4, 6 months) or WHO schedule (6, 10, 14 weeks). Both groups will receive IPV at visits 1, 2 and 3. Infants will receive all age-appropriate EPI childhood vaccinations along with IPV, to decrease confusion and inconvenience to the parent. Serum will be collected twice, at visit 1 and visit 4 (30-45 days after IPV-3), to measure antibody titers. Sera will be measured for neutralizing antibodies at the Centers for Disease Control (CDC). Based on the lowest seroconversion rate estimate of 85%, and to have a probability of .80 that the estimate from this study is in error by no more than 10%, the investigators will need to enroll 220 infants in each arm. To compensate for attrition and retain statistical power, the investigators plan to enroll up to 250 infants in each arm. This study is expected to require at least 20 months to complete. Results will provide valuable and timely information applicable to global polio eradication efforts. Any participant found not to be protected after 3 doses of IPV will be given a booster at 9-12 months. Results will provide valuable and timely information applicable to global polio eradication efforts.