The National Register of Health Service Psychologists (abbreviated National Register) (formerly National Register of Health Service Providers in Psychology) is the largest credentialing organization for psychologists in the United States. Founded in 1974, the National Register was created to identify qualified Health Service Providers. Today, the National Register certifies 11,000 licensed psychologists as health service providers and reviews credentials for doctoral students. The National Register is a 501c3 nonprofit organization based in Washington DC.