BACKGROUND AND OBJECTIVE: Although effective in preventing pneumococcal disease, 13-valent pneumococcal conjugate vaccine (PCV13) is the most expensive vaccine on the routinely recommended pediatric schedule in the United States. We examined the cost-effectiveness of switching from 4 total doses to 3 total doses by removing the third dose in the primary series in the United States. METHODS: We used a probabilistic model following a single birth cohort of 4.3 million to calculate societal cost savings and increased disease burden from removing the 6-month dose of PCV13. Based on modified estimates of 7-valent pneumococcal conjugate vaccine from randomized trials and observational studies, we assumed that vaccine effectiveness under the 2 schedules is identical for the first 6 months of life and largely similar after administration of the 12- to 15-month booster dose. RESULTS: Removing the third dose of PCV13 would annually save $500 million (in 2011$) but would also result in an estimated 2.5 additional deaths among inpatients with pneumonia or invasive pneumococcal disease. Such dose removal would also result in 261 000 estimated otitis media and 12 000 estimated pneumonia cases annually. These additional illnesses could be prevented through modest increases in coverage. Overall, societal savings per additional life-year lost would be ∼$6 million. When nonfatal outcomes are also considered, savings would range from $143 000 to $4 million per additional quality adjusted life-year lost, depending on the assumptions used for otitis media. CONCLUSIONS: Sizable societal cost savings and a moderate pneumococcal disease increase could be expected from removing the PCV13 primary series’ third dose.