In contrast to earlier pneumococcal vaccines, conjugate vaccines hold promise for reducing pneumococcal morbidity and mortality in infants and young children. The first commercially available conjugate vaccine formulation, which targets seven serotypes, was licensed in the US and other countries in 2000; this vaccine is now part of routine infant immunization in the US. Demand has been high and greater than vaccine supply. Clinical trials indicate that conjugate vaccines are highly efficacious against invasive pneumococcal disease and modestly efficacious against otitis media and pneumonia. In carriage studies conjugate vaccines reduced vaccine-type carriage but led to an increase in carriage of other serotypes. Remaining questions include whether less frequent transmission of vaccine serotypes will mean less disease in unvaccinated children and adults or if nonvaccine serotypes will begin to cause more disease. Monitoring disease burden after widespread use in the US is critical for understanding the effects of the vaccine. In addition making pneumococcal vaccines available for children in developing countries should be a high priority.