CMS announced the implementation of enumeration for the National Provider Identifier (NPI). The NPI is the standard unique health identifier for health care providers that was adopted by the Secretary of Health and Human Services under the Health Insurance Portability and Accountability Act of 1996. CMS’s announcement letter informs health care providers about the NPI, describes three ways to obtain an NPI, and gives them guidance as to what they should do once they have obtained their NPI.