BACKGROUND The childhood burden of disease attributable to Streptococcus pneumoniae is particularly high in India. The immunogenicity and safety of 13-valent pneumococcal conjugate vaccine (PCV13) were compared with 7-valent pneumococcal conjugate vaccine (PCV7) in a randomized, active-controlled, double-blind trial conducted at 12 sites in India. METHODS Healthy infants received PCV13 or PCV7 at 6, 10, and 14 weeks of age (infant series) and at 12 months of age (toddler dose), along with routine pediatric vaccinations. Immunoglobulin G responses against the 13 pneumococcal serotypes were evaluated 1 month after the infant series and after the toddler dose. Pertussis and poliomyelitis immune responses were assessed 1 month after the infant series. Safety and tolerability also were assessed. RESULTS The immunogenicity results for the 7 common serotypes and the concomitant vaccines (whole-cell pertussis and oral poliovirus) were similar for subjects receiving PCV13 and subjects receiving PCV7. Immune responses to the 6 additional serotypes were higher in the PCV13 group compared with the PCV7 group. PCV13 and PCV7 had similar safety and tolerability profiles. CONCLUSIONS PCV13 has immunogenicity similar to PCV7 in response to the 7 common serotypes, and has generally higher immunogenicity in response to the 6 additional serotypes. PCV13 may provide added protection against pneumococcal disease caused by the additional 6 serotypes and does not interfere with immune responses to whole-cell pertussis and oral poliovirus vaccines. PCV13 has an acceptable safety profile in both infants and toddlers, comparable with that of PCV7.