Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
William Michael Arnold
Behavior Analyst in Joliet, IL · enumerated 2008.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1366687543
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Registry record
Entity type Individual (Type 1)
Name William Michael Arnold
Sex Male
Practice address 777 Joyce Rd, Joliet, IL, 60436
Phone (815) 727-6666
Fax (815) 723-1177
Enumeration date Dec 2, 2008
Last updated in NPPES Dec 2, 2008
Taxonomy & licenses
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
Where does William Arnold practice?
The practice location on file with NPPES is in Joliet, IL. Providers can have multiple locations; NPPES lists the primary practice address.
What is the NPI number for William Arnold?
The National Provider Identifier (NPI) for William Arnold is 1366687543, a Type 1 (individual) record in the CMS NPPES registry.
Other providers at this practice address
Browse all → Cornerstone Services Inc Mental Health Clinic/Center (Including Community Mental Health Center) · Joliet, IL NPI 1205816345 Michael Malkusak Specialist · Joliet, IL NPI 1881854586 Nick Turton Specialist · Joliet, IL NPI 1215198106 Victoria Pellettiere Behavior Analyst · Joliet, IL NPI 1447570536 Kathryn Grella Social Worker · Joliet, IL NPI 1518278704 Nicole Koren Behavior Analyst · Joliet, IL NPI 1740567502 Mulan Dai Behavior Analyst · Joliet, IL NPI 1679850184 Louis Sandler Behavior Analyst · Joliet, IL NPI 1710321609
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2008-12-02.