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Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor

Marianna Zara Grennan, LCSW R

Clinical Social Worker in Melville, NY · enumerated 2008 · practices at Landing Meadows Mental Health Counseling Pllc.

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

National Provider Identifier

1013188390

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Registry record

Entity type Individual (Type 1)
Name Marianna Zara Grennan
Credential LCSW R
Sex Female
Practice address Melville, NY, 11747
Phone (631) 271-5617
Fax (631) 385-1776
Enumeration date Mar 14, 2008
Last updated in NPPES Mar 14, 2008

Street address withheld: NPPES sole-proprietor addresses can be home addresses. See our data policy.

Taxonomy & licenses

1041C0700X Clinical Social Worker Behavioral Health & Social Service Providers · License R049385 (NY) Primary

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.

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Frequently asked questions

What is the NPI number for Marianna Grennan?
The National Provider Identifier (NPI) for Marianna Grennan is 1013188390, a Type 1 (individual) record in the CMS NPPES registry.
Where does Marianna Grennan practice?
The practice location on file with NPPES is in Melville, NY. Providers can have multiple locations; NPPES lists the primary practice address.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2008-03-14.