Tess Gelderloos, MA, BCBA LBA

Primary specialty

Behavior AnalystTaxonomy code 103K00000X

License

1-14-16072 Issued in MT

Practice address

1601 2ND Ave N Ste 700
Great Falls, MT 59401-3288

Phone

(406) 205-0452

Fax

(406) 545-2276

NPI assigned

Nov 15, 2014

Sex

Female

Sole proprietor

No

Registry information is reported by the provider to CMS and is not verified. About this source

Specialties & licenses 1

Addresses

Medicare fee-for-service enrollment

Not listed in the public Medicare enrollment file

Medicare enrollment (NPD)

Not enrolled

Credentials

Master of Arts

Practice roles

Organizations this provider is connected to: Medicare benefit reassignments (the organization bills Medicare for this provider’s services), Care Compare group memberships and National Provider Directory roles.

• Spectrum Behavioral Services PLLC

  • Behavior Analyst
  • Livingston, MT
  • NPI 1972230209
  NPD Authorized official
• Big Sky Therapeutic Services, PLLC

  • Community/Behavioral Health Agency
  • Great Falls, MT
  • NPI 1588966584

  Behavior Analyst

  NPD (past)

The complete NPPES record for this NPI in the NPI Registry API format.

{
    "created_epoch": "1416009600000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1770595200000",
    "number": "1144626342",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "1240 116TH AVE NE STE 102",
            "city": "BELLEVUE",
            "state": "WA",
            "postal_code": "980043815",
            "telephone_number": "206-437-5412"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "1601 2ND AVE N STE 700",
            "city": "GREAT FALLS",
            "state": "MT",
            "postal_code": "594013288",
            "telephone_number": "406-205-0452",
            "fax_number": "406-545-2276"
        }
    ],
    "practiceLocations": [],
    "basic": {
        "last_name": "GELDERLOOS",
        "first_name": "TESS",
        "credential": "MA, BCBA LBA",
        "sole_proprietor": "NO",
        "sex": "F",
        "enumeration_date": "2014-11-15",
        "last_updated": "2026-02-09",
        "certification_date": "2026-02-09",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "103K00000X",
            "taxonomy_group": "",
            "desc": "Behavior Analyst",
            "state": "MT",
            "license": "1-14-16072",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [],
    "other_names": []
}

• Leandra Rose Gebhardt, DPT
• Maria K Gee, P.T.
• Mary B Geer
• Diane L Geisen, M.S.W., L.C.S.W.
• Gerald Irvin Geiszler, M.D.
• Joy Lynne Geller, LMT
• Genesis Rehabilitation
• Genesis Rehabilitation
• Gensis Rehabilitation
• Gentle Beginnings Family Birth Center Inc

• All providers in Great Falls, MT
• Behavior Analyst in Montana

• NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Feb 9, 2026; self-reported and not verified by CMS. Specialty names from the NUCC taxonomy.
• National Provider Directory (CMS): practice roles, locations, licenses, networks and endpoints.

Verify at the official NPI Registry.