Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Diane Sizer, PH.D.

Psychologist in Southampton, PA · enumerated 2006.

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

National Provider Identifier

1265478259

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Registry record

Entity type Individual (Type 1)

Name Dr. Diane Sizer

Credential PH.D.

Sex Female

Practice address 928 Jaymor Rd Ste B-150, Southampton, PA, 18966

Phone (215) 947-8654

Fax (215) 938-7607

Enumeration date Jun 20, 2006

Last updated in NPPES Jul 3, 2024

Taxonomy & licenses

103T00000X Psychologist Behavioral Health & Social Service Providers · License PS-008239-L (PA) Secondary

103T00000X Psychologist Behavioral Health & Social Service Providers · License PS008239L (PA) Primary

PHD · Doctor of Philosophy: A doctoral degree; in healthcare often held by clinical psychologists and researchers. About the PHD credential

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 → Validate an NPI →

Frequently asked questions

Is NPI 1265478259 active?

Yes, as of the latest NPPES snapshot, NPI 1265478259 is active (record last updated 2024-07-03).

How do I verify Diane Sizer's NPI record?

Cross-check NPI 1265478259 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2024-07-03.