The purpose of this document is to define and provide supporting references to the Immunization Information System (IIS) Functional Standards for 2013-2017. These standards have been developed by the Immunization Information Systems Support Branch, CDC/NCIRD, through a consensus process involving input from a variety of IIS managers and technical experts from across the U.S (Appendix A). In recognition of the growing importance of IIS to the broader Health Information Technology landscape, the revised standards are intended to lay a framework for the development of IIS through 2017. These standards supersede the “Minimum Functional Standards for Registries” adopted by the National Vaccine Advisory Committee (NVAC) in 2001.