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

Marvin Darnell Graddy

Addiction (Substance Use Disorder) Psychologist in Antioch, CA · enumerated 2021.

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

National Provider Identifier

1144805011

Verified

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Registry record

Entity type Individual (Type 1)

Name Marvin Darnell Graddy

Sex Male

Practice address Antioch, CA, 94531

Phone (925) 334-9906

Enumeration date Mar 12, 2021

Last updated in NPPES Mar 12, 2021

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 · License 101YA0400X (CA) Secondary

101YM0800X Mental Health Counselor Behavioral Health & Social Service Providers · License 101YA0400X (CA) Secondary

103TA0400X Addiction (Substance Use Disorder) Psychologist Behavioral Health & Social Service Providers · License 101YA0400X (CA) Primary

Other identifiers

Identifier	Type	State	Issuer
5VE8-FC6-UP53	Medicaid	CA	-

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

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

What specialty is Marvin Graddy?

Marvin Graddy is registered in NPPES with the primary taxonomy of Addiction (Substance Use Disorder) Psychologist. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2021-03-12.