DR. MICHAEL ANDREW WILLISTON PSY.D.
NPI 1093090474
Psychologist in Wilmington, DE

Active since October 17, 2011PECOS EnrolledAccepts Medicare Assignment
4000 NEXUS DR STE NE3-100, WILMINGTON, DE 19803(302) 320-9771(302) 623-7964 Get Directions Write a Review

NPPES record last updated: January 13, 2025. Verified against the NPPES registry weekly; last sync: October 18, 2026.

About Dr. Michael Andrew Williston Psy.d. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

DR. MICHAEL ANDREW WILLISTON PSY.D. (NPI 1093090474) is an individual psychologist in Wilmington, Delaware, licensed in Delaware (B1-0011487) and active in the NPI registry since October 2011. He is enrolled in Medicare PECOS, maintains a secondary practice location in Philadelphia, and is a graduate of Other (2011).

NPPES Registry Identity

NPI1093090474
Entity TypeIndividualMale
Primary Taxonomy103T00000X
Provider Legal NameDR. MICHAEL ANDREW WILLISTONCredential: PSY.D.
Location Address4000 NEXUS DR STE NE3-100Wilmington, DE 19803-3000
Mailing Address112 N Broad StPhiladelphia, PA 19102-1512 · (215) 568-0860
Fax(302) 623-7964
Sole ProprietorNo
Medical School CMSOtherGraduated 2011
Enumeration DateOctober 17, 2011
Last NPPES UpdateJanuary 13, 2025
NPPES CertifiedJanuary 13, 2025
✔ NPI 1093090474 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyPsychologistBehavioral Health & Social Service Providers
Taxonomy Code103T00000X
Licenses✔ Licensed in DE · B1-0011487✔ Licensed in PA · PS017269
Definition
A psychologist is an individual who is licensed to practice psychology which is defined as the observation, description, evaluation, interpretation, and modification of human behavior by the application of psychological principles, methods, and procedures, for the purpose of preventing or eliminating symptomatic, maladaptive, or undesired behavior and of enhancing interpersonal relationships, work and life adjustment, personal effectiveness, behavioral health, and mental health. The practice of psychology includes, but is not limited to, psychological testing and the evaluation or assessment of personal characteristics, such as intelligence, personality, abilities, interests, aptitudes, and neuropsychological functioning; counseling, psychoanalysis, psychotherapy, hypnosis, biofeedback, and behavior analysis and therapy; diagnosis and treatment of mental and emotional disorder or disability, alcoholism and substance abuse, disorders of habit or conduct, as well as of the psychological aspects of physical illness, accident, injury, or disability; and psycheducational evaluation, therapy, remediation, and consultation. Psychological services may be rendered to individuals, families, groups and the public.
4000 NEXUS DR STE NE3-100, Wilmington, DE 19803

Other Names 1

Former Name (1)Mr. Michael Andrew Holston

Secondary Practice Location 1

Location 1112 N Broad StPhiladelphia, PA 19102-1512 · Phone (215) 568-0860

Accepted Insurance

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Dr. Michael Andrew Williston Psy.d. is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.

PECOS PAC ID6204074065
PECOS Enrollment IDI20250114000738
Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment– Home Health Agency– Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignments

2

Medicare enrollment records show Michael Williston reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Family Medicine
1401 FOULK RD, SUITE 100B
Wilmington, DE 19803
  • Reassigned Medicare billing, Delaware enrollment
  • 1,531 clinicians in this Medicare group
Family Medicine
501 W 14TH ST
Wilmington, DE 19801
  • Reassigned Medicare billing, Delaware enrollment
  • 28 clinicians in this Medicare group

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Other Providers at the Same Location NPPES 4

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

Physician Assistant
4000 NEXUS DR STE NE3-100
WILMINGTON, DE 19803
Nurse Practitioner (Family)
4000 NEXUS DR STE NE3-100
WILMINGTON, DE 19803
Internal Medicine (Pulmonary Disease)
4000 NEXUS DR STE NE3-100
WILMINGTON, DE 19803
Social Worker (Clinical)
4000 NEXUS DR STE NE3-100
WILMINGTON, DE 19803

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Michael Williston's NPI number?

The NPI number for Michael Williston is 1093090474. It was assigned to this individual provider in the NPPES registry on October 17, 2011. The provider is also known as Mr. Michael Andrew Holston.

Where is Michael Williston located?

Michael Williston practices at 4000 Nexus Dr Ste Ne3-100, Wilmington, DE 19803. The listed phone number is (302) 320-9771.

What is Michael Williston's specialty?

The primary specialty registered for this NPI is Psychologist with taxonomy code 103T00000X.

Is Michael Williston enrolled in Medicare?

Yes. Michael Williston is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.

Which organizations bill Medicare for Michael Williston's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Michael Williston reassigns Medicare benefits to 2 organizations: Christiana Care Health Services, Inc (Wilmington, DE) and Christianacare Virtual Health Practice PA (Wilmington, DE). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Michael Williston's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

What insurance does Michael Williston accept?

Health plans from Ambetter Health, Ambetter Health of Delaware, Ambetter from NH Healthy Families and Ambetter from Sunflower Health Plan list Michael Williston as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.

When was this NPI record last updated?

The NPPES record for Michael Williston was last updated on January 13, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 21 months ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.