Type 2 · Organization ✓ Active NPI ✓ Valid NPI checksum Organization subpart

Internal Medicine Associates at Princeton, LLC

Internal Medicine Physician in Princeton, NJ · enumerated 2007 · authorized official Mark Schaeffer, President.

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

National Provider Identifier

1285775114

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Registry record

Entity type Organization (Type 2)

Legal business name Internal Medicine Associates at Princeton, LLC

Parent organization Princeton Internal Medicine Associates, PC

Practice address 281 Witherspoon St, Suite 220, Princeton, NJ, 08540

Phone (609) 921-3362

Fax (609) 921-3584

Enumeration date Feb 12, 2007

Last updated in NPPES Jul 2, 2010

Taxonomy & classification

207R00000X Internal Medicine Physician Allopathic & Osteopathic Physicians Primary

Authorized official

Name Mark Schaeffer

Title President

Phone (609) 921-3362

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 Internal Medicine Associates at Princeton, LLC?

The NPI for Internal Medicine Associates at Princeton, LLC is 1285775114, a Type 2 (organization) record in the CMS NPPES registry.

Who is the authorized official for Internal Medicine Associates at Princeton, LLC?

NPPES lists Mark Schaeffer (President) as the authorized official for this organization.

Providers at this address

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2010-07-02.