Vaccine-preventable disease continues to take a heavy toll on adults despite the widespread availability of effective vaccines. This report identifies where efforts to improve the delivery of adult vaccination have stalled and recommends targeted strategies that are supported by available evidence and build on existing infrastructure. The authors conducted a comprehensive review of the published literature on adult immunization, a stakeholder workshop, and follow-up interviews with meeting participants and additional experts. They also partnered with an organization represented at the workshop to conduct a telephone survey of adults to learn about the relationship between influenza vaccination and beliefs about the safety of influenza vaccine.