Adherence to recommendations for the use of licensed vaccines ensures maximum individual and societal benefits from the national immunization program. The US Food and Drug Administration (FDA) licenses a vaccine once it determines that data submitted by the manufacturer reveal that the vaccine is safe and effective for its intended use. For each US-licensed vaccine, the FDA-approved prescribing information contains detailed information for health care providers to ensure safe and effective use. Centers for Disease Control and Prevention recommendations for the use of a licensed vaccine often are based on additional considerations, such as disease epidemiology, public acceptance, vaccine supply, and cost. Our objective in this article is to explain the reasons for the differences between FDA-approved prescribing information and Centers for Disease Control and Prevention recommendations for vaccine use.