Robert Williams, PH.D.
Robert Williams, PH.D. is a Psychologist in South San Francisco, CA, registered under NPI 1669614723. This provider registers 6 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 1115 MISSION RD, South San Francisco, CA 94080. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 21573 | CA | Psychologist primary |
| 21573 | CA | Addiction (Substance Use Disorder)… |
| 21573 | CA | Clinical Psychologist |
| 21573 | CA | Counseling Psychologist |
| 21573 | CA | Clinical Child & Adolescent Psychologist |
| 21573 | CA | Family Psychologist |
This provider holds licence 21573 issued in CA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
What Psychologist covers
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. NUCC Health Care Provider Taxonomy, code 103T00000X
All registered taxonomy codes
This provider registers 6 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 103T00000X | Psychologist | 21573 | CA | primary |
| 103TA0400X | Addiction (Substance Use Disorder) Psychologist Addiction (Substance Use Disorder) | 21573 | CA | |
| 103TC0700X | Clinical Psychologist Clinical | 21573 | CA | |
| 103TC1900X | Counseling Psychologist Counseling | 21573 | CA | |
| 103TC2200X | Clinical Child & Adolescent Psychologist Clinical Child & Adolescent | 21573 | CA | |
| 103TF0000X | Family Psychologist Family | 21573 | CA |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1669614723 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Apr 3, 2009 |
| Last updated | Apr 3, 2009 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | PH.D. |
| Practice address |
1115 MISSION RD South San Francisco, CA 94080 (415) 509-6734 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 6 | 6 | 9 | 6 | 1 | 4 | 7 | 2 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 6 | 3 | 9 | 3 | 1 | 8 | 7 | 4 |
Sum = 67 · next multiple of 10 = 70 · check digit = 3 · actual last digit = 3
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.