Dr. Mark Williams Stevens, PH.D.
Dr. Mark Williams Stevens is a Clinical Psychologist provider (Psychologist) practicing in Poway, CA, registered in the NPPES registry with NPI 1336269398 since 2007. The credential PHD stands for Doctor of Philosophy.
✓ Active NPI ✓ Valid NPI checksum Sole proprietor
| NPI | 1336269398 |
|---|---|
| Entity type | Individual (Type 1) |
| Name | Dr. Mark Williams Stevens |
| Credential | PH.D. |
| Sex | Male |
| Practice address | Poway, CA, 92064 |
| Phone | 8582078322 |
| Fax | 8587488050 |
| Enumeration date | 2007-03-30 |
| Last updated in NPPES | 2007-07-08 |
Street address withheld — NPPES sole-proprietor addresses can be home addresses. See our data policy.
Taxonomy & licenses
| Taxonomy code | Specialty | Primary | License | State |
|---|---|---|---|---|
| 103TC0700X | Clinical Psychologist | Primary | 20859 | CA |
PHD — Doctor of Philosophy: A doctoral degree; in healthcare often held by clinical psychologists and researchers. About the PHD credential
Copy-ready billing details
Provider: Mark Stevens, PH.D. NPI: 1336269398 Taxonomy: 103TC0700X (Clinical Psychologist) Address: Poway, CA, 92064
Other providers at this practice address
| NPI | Name | Type | Specialty | Location |
|---|---|---|---|---|
| 1235132127 | William Combs | Individual | Dentist | Poway, CA |
| 1215018718 | Jay Dickson | Individual | Chiropractor | Poway, CA |
| 1518024470 | Mary Ann Neumann | Individual | Marriage & Family Therapist | Poway, CA |
| 1093910069 | Deborah Lewallen | Individual | Marriage & Family Therapist | Poway, CA |
| 1932371507 | Lorenzo Munoz | Organization | Internal Medicine Physician | Poway, CA |
| 1861727372 | Poway Medical Clinic, Incorporated | Organization | Primary Care Clinic/Center | Poway, CA |
| 1598056392 | Silvia Grindle | Individual | Physician Assistant | Poway, CA |
| 1548520471 | San Diego Psychological & Educational Services Inc | Organization | Clinical Psychologist | Poway, CA |
Verify this record
Cross-check NPI 1336269398 against the authoritative CMS record: view Dr. Mark Williams Stevens on the official NPPES registry .
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. Read the full guide or validate an NPI number.
Frequently asked questions
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Source: CMS NPPES (public data). Snapshot 2026-07-11. Provider record last updated 2007-07-08.