Immunization is one of the most effective public and private preventive health interventions, resulting in significant reductions in vaccine-preventable diseases and in substantial cost savings to the US healthcare system. Vaccine licensure, development of recommendations for use, and implementation of those recommendations leading to uptake, community protection, and effect on disease burden represent a complex system that requires collaboration in the areas of basic science, public health, vaccine delivery, outcome monitoring, and public perception. The Advisory Committee on Immunization Practices (ACIP) sets standards for immunization delivery for both public and private vaccine providers, and state immunization programs can use these ACIP recommendations to develop school immunization requirements.