Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor

James Donald Williamson

Addiction (Substance Use Disorder) Counselor in South San Francisco, CA · enumerated 2014.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1174934012

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Registry record

Entity type Individual (Type 1)

Name James Donald Williamson

Sex Male

Practice address South San Francisco, CA, 94080

Phone (650) 244-1447

Fax (650) 244-1447

Enumeration date May 14, 2014

Last updated in NPPES May 14, 2014

Street address withheld: NPPES sole-proprietor addresses can be home addresses. See our data policy.

Taxonomy & licenses

101YA0400X Addiction (Substance Use Disorder) Counselor Behavioral Health & Social Service Providers Primary

Other identifiers

Identifier	Type	State	Issuer
AD418603	Other	CA	ENTREFAMILIA
AD414903	Other	-	ENTRE FAMILIA IOP
97037	Other	CA	CASA OLLIN

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

What is the NPI number for James Williamson?

The National Provider Identifier (NPI) for James Williamson is 1174934012, a Type 1 (individual) record in the CMS NPPES registry.

Where does James Williamson practice?

The practice location on file with NPPES is in South San Francisco, CA. Providers can have multiple locations; NPPES lists the primary practice address.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2014-05-14.