Matthew Craig Williams, MD
Child & Adolescent Psychiatry Physician · Mill Valley, CA
Matthew Craig Williams, MD is a child & adolescent psychiatry physician with a practice address in Mill Valley, California, and NPI 1326626797, issued on Mar 29, 2021. Check the license (California A186478, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Matthew Craig Williams
- Credential
- MD
- Primary taxonomy
- Child & Adolescent Psychiatry Physician 2084P0804X
- License number
- A186478 CA
Self-reported in NPPES; status is on the state search - Practice location
- 655 Redwood Hwy Frontage RD Ste 261, Mill Valley, CA 94941
- Phone
- (415) 381-1690
- Enumerated
- Mar 29, 2021
- Record last updated
- Jun 9, 2026
- Medicare enrollment
- Enrolled (PECOS I20231109003422); accepts Medicare assignment
- Medical or professional school
- Georgetown University School Of Medicine, 2021
- Entity
- Type 1 · individual
8 nearest child & adolescent psychiatry physician records → All 1,009 in California → Look up another NPI →
Also registered at 655 Redwood Hwy Frontage RD Ste 261
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Michael Ramsey, D.O.Child & Adolescent Psychiatry Physician1205052693
- Brittany Smith, MDPsychiatry Physician1164088118
Verify Matthew Craig Williams in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A186478Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
25% more Medicare Part D claims than the average child & adolescent psychiatry physician in 2024
630 Medicare Part D claims for 59 beneficiaries, against an average of 504 among the 3,545 providers of this specialty who prescribed in Part D. Brand-name drugs were 3% of claims.
Most prescribed
- Bupropion Xl98 claims
- Duloxetine Hcl64 claims
- Mirtazapine33 claims
- Sertraline Hcl25 claims
- Aripiprazole24 claims
- Clonazepam22 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Bills Medicare through one group practice
- Bay Psychiatric AssociatesBerkeley, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Matthew Craig Williams among 1,009 child & adolescent psychiatry physician records in California
Matthew Craig Williams, MD is one of 1,009 child & adolescent psychiatry physician records with a practice address in California. 55% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2021, is newer than 96% of them.
- NPI issued2021 · 96% of these records are older, 3% newer
- In a Medicare fileYes · 55% of these records are
- In the CMS Doctors and Clinicians fileYes · 21% of these records are
- Graduated2021 · median 2005 among the 215 with a school on file
- Record last updated2026 · 57% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 2084P0804X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Child & Adolescent Psychiatry Physician providers in California
There are 1,009 child & adolescent psychiatry physician records in California.
All 1,009 in California → Every provider in Mill Valley → Child & Adolescent Psychiatry Physician nationwide →
The 8 child & adolescent psychiatry physician records with the nearest ZIP codes
- Michael Ramsey, D.O.Mill Valley, CA 949411205052693
- Chelsea Young, MDMill Valley, CA 949411942695754
- Zachary Schwab, MDLarkspur, CA 949391255862181
- Margaret Grimley, M.D.Petaluma, CA 949521558461095
- Susie Shin-Calandrella, MDPetaluma, CA 949521790859775
- Kenneth Wulff, MDPetaluma, CA 949521124105085
- Mario Mangiardi, MDPetaluma, CA 949541023490828
- Dannah Hirsch, M.D., M.P.H.Corte Madera, CA 949251326259680
Common questions
What is Matthew Craig Williams, MD's NPI number?
Matthew Craig Williams, MD's National Provider Identifier (NPI) is 1326626797, issued on Mar 29, 2021. An NPI identifies a provider in billing; it is not a license.
Where is Matthew Craig Williams, MD located?
The NPPES record lists a practice address at 655 Redwood Hwy Frontage RD Ste 261, Mill Valley, CA, 94941. Phone: (415) 381-1690. Providers update this record themselves, so call before visiting.
How can I verify Matthew Craig Williams, MD's license?
NPPES lists California license number A186478, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Matthew Craig Williams, MD prescribe under Medicare Part D?
In 2024, Matthew Craig Williams, MD had 630 Medicare Part D claims for 59 beneficiaries; the average among child & adolescent psychiatry physician prescribers was 504. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.