Pneumococcal pneumonia is concentrated among the elderly. Using a decision analytic model, we projected the future incidence of pneumococcal pneumonia and associated healthcare utilization and costs accounting for an aging US population. Between 2004 and 2040, as the population increases by 38%, pneumococcal pneumonia hospitalizations will increase by 96% (from 401 000 to 790 000), because population growth is fastest in older age groups experiencing the highest rates of pneumococcal disease. Absent intervention, the total cost of pneumococcal pneumonia will increase by $2.5 billion annually, and the demand for healthcare services for pneumococcal pneumonia, especially inpatient capacity, will double in coming decades.