Mark Clay Williams, PHD
Clinical Psychologist · Altamonte Springs, FL
Mark Clay Williams, PHD is a clinical psychologist with a practice address in Altamonte Springs, Florida, and NPI 1619998416, issued on Jul 21, 2006. Check the license (Florida PY0003957, as entered in NPPES) on the Florida health license search; the Medicare figures below come from public CMS files.
- Name
- Mark Clay Williams
- Credential
- PHD
- Primary taxonomy
- Clinical Psychologist 103TC0700X
- License number
- PY0003957 FL
Self-reported in NPPES; status is on the state search - Practice location
- 989 Orienta Ave, Altamonte Springs, FL 32701
- Phone
- (407) 831-3446
- Enumerated
- Jul 21, 2006
- Record last updated
- Jul 8, 2007 (not updated in 19 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest clinical psychologist records → All 2,980 in Florida → Look up another NPI →
Also registered at 989 Orienta Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Eduardo Diaz, M.D.Geriatric Medicine (Family Medicine) Physician1902043771
Verify Mark Clay Williams in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersFlorida health license search
Search for license PY0003957Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
The practice group's MIPS final score for 2023 (Medicare payment program): 100 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023, group reporting; category weights for 2023 (qpp.cms.gov).
Mark Clay Williams among 2,980 clinical psychologist records in Florida
Mark Clay Williams, PHD is one of 2,980 clinical psychologist records with a practice address in Florida. 14% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 3% of them.
- NPI issued2006 · 3% of these records are older, 74% newer
- In a Medicare fileYes · 14% of these records are
- In the CMS Doctors and Clinicians fileNo · 26% of these records are
- Record last updated2007 · 63% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 103TC0700X and a Florida practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Clinical Psychologist providers in Florida
There are 2,980 clinical psychologist records in Florida.
All 2,980 in Florida → Every provider in Altamonte Springs → Clinical Psychologist nationwide →
The 8 clinical psychologist records with the nearest ZIP codes
- Sean Jennings, PSY.D.Altamonte Springs, FL 327011528278611
- Alice Lovell, PH.D., RNAltamonte Springs, FL 327011033451026
- Nicole Maggio, PSY.D.Altamonte Springs, FL 327011588822753
- Deborah Smith, PSY.D.Altamonte Springs, FL 327011821130683
- Daniel Tressler, PSYDAltamonte Springs, FL 327011649323171
- Louis Mavrides, PH.D.Apopka, FL 327031124117379
- Jordan Calloway, PSY.D.Casselberry, FL 327071619244571
- Barbara Cloues, PHDCasselberry, FL 327071154395283
Common questions
What is Mark Clay Williams, PHD's NPI number?
Mark Clay Williams, PHD's National Provider Identifier (NPI) is 1619998416, issued on Jul 21, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Mark Clay Williams, PHD located?
The NPPES record lists a practice address at 989 Orienta Ave, Altamonte Springs, FL, 32701. Phone: (407) 831-3446. Providers update this record themselves, so call before visiting.
How can I verify Mark Clay Williams, PHD's license?
NPPES lists Florida license number PY0003957, as entered by the provider. Search the Florida health license search at https://mqa-internet.doh.state.fl.us/mqasearchservices/healthcareproviders. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
What is Mark Clay Williams, PHD's MIPS final score?
The 2023 MIPS final score is 100 of 100, reported for the practice group. The average among 454,083 clinicians with a measured score was 83.5.
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.