In 2010, 13-valent pneumococcal conjugate vaccine (PCV13 [Prevnar 13, Wyeth Pharmaceuticals, Inc., a subsidiary of Pfizer, Inc.]) was licensed by the Food and Drug Administration (FDA) and recommended by the Advisory Committee on Immunization Practices (ACIP) for children aged 6 weeks through 71 months for the prevention of invasive pneumococcal disease (IPD) caused by the 13 pneumococcal serotypes included in the vaccine. PCV13 currently is recommended as a 4-dose series for children starting at age 2 months. On December 30, 2011, FDA approved PCV13 for prevention of pneumonia and invasive disease caused by PCV13 serotypes among adults aged 50 years and older. This report summarizes data on the immunogenicity and safety of PCV13 in adults and outlines key additional evidence requested by ACIP to formulate recommendations for its use.