Type 2 · Organization ✓ Active NPI ✓ Valid NPI checksum

Cornerstone Developmental Psychology

Q: What is the NPI number for Cornerstone Developmental Psychology?

The NPI for Cornerstone Developmental Psychology is 1336673318, a Type 2 (organization) record in the CMS NPPES registry.

Psychologist in Hauppauge, NY · enumerated 2017 · authorized official Mark Closson, Psychologist.

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

National Provider Identifier

1336673318

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Registry record

Entity type Organization (Type 2)

Legal business name Cornerstone Developmental Psychology

Practice address 750 Vets Hwy, Suite 202, Hauppauge, NY, 11788

Phone (631) 925-1003

Enumeration date Apr 17, 2017

Last updated in NPPES Apr 17, 2017

Taxonomy & classification

103T00000X Psychologist Behavioral Health & Social Service Providers Primary

104100000X Social Worker Behavioral Health & Social Service Providers Secondary

Authorized official

Name Mark Closson

Title Psychologist

Phone (631) 925-1003

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

What is the NPI number for Cornerstone Developmental Psychology?

The NPI for Cornerstone Developmental Psychology is 1336673318, a Type 2 (organization) record in the CMS NPPES registry.

Who is the authorized official for Cornerstone Developmental Psychology?

NPPES lists Mark Closson (Psychologist) as the authorized official for this organization.

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2017-04-17.