Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Dr. William J. A. O'Brien, PSY.D
Psychologist in Westborough, MA · enumerated 2014.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1255740254
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Registry record
Entity type Individual (Type 1)
Name Dr. William J. A. O'Brien
Credential PSY.D
Sex Male
Practice address 288 Lyman St, Second Floor, Westborough, MA, 01581
Phone (508) 475-2626
Enumeration date Aug 5, 2014
Last updated in NPPES Aug 5, 2014
Taxonomy & licenses
PSYD · Doctor of Psychology: A clinical doctorate in psychology focused on professional practice.
About the PSYD 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.
Frequently asked questions
What specialty is William O'Brien?
William O'Brien is registered in NPPES with the primary taxonomy of Psychologist. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.
Is this the official NPI registry?
No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.
Other providers at this practice address
Browse all → Kenneth Mitchell Psychiatry Physician · Westborough, MA NPI 1386744787 Department of Mental Health Psychiatric Hospital · Westboro, MA NPI 1881787455 Alan Bodnar Clinical Psychologist · Westborough, MA NPI 1235219627 The Commonwealth of Massachusetts Psychiatric Hospital · Westborough, MA NPI 1740358878 John Toomey Internal Medicine Physician · Westborough, MA NPI 1558426262 Steven Strassberg Clinical Psychologist · Westborough, MA NPI 1265589824 Charlotte Boutillette Occupational Therapy Assistant · Westborough, MA NPI 1629129234 Abigail Perham Mental Health Counselor · Westborough, MA NPI 1942346986
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2014-08-05.