In practice, specialty service providers are identified mainly via administrative records related to public funding, licensing, or other regulatory functions performed by State and Federal agencies.
Federal agencies participate by providing lists of providers.
Prior to the 1992 survey, the NFR identified 12,331 specialty treatment providers. Prior to the 1992 survey, the NFR identified 2,412 non-treatment providers. Since the 1980 survey, the reference date has been at the end of September, with the exception of 1987 when it was at the end of October. These updated NFR records are updated a second time, by providers themselves, when they are pre-printed on page one of each form that is mailed to providers. Survey forms were mailed to the States on September 15, for subsequent distribution to providers.