Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Mark Nahnsen, LCSW

Individual provider Clinical Social Worker · NPI 1831480128

Mark Nahnsen, LCSW is a Clinical Social Worker in Woodstock, New York. Practices as a sole proprietor. Licensed in New York.

Licensed in
NY
In the registry since
2011
What do these letters mean?
LCSW — Licensed Clinical Social Worker
A social worker licensed to diagnose and treat mental health conditions independently.

See every abbreviation used in this directory →

Practice location Address checks out

339 Ohayo Mountain Rd
Woodstock, NY 12498-2519
Phone: (845) 679-6429
Fax: (845) 331-4875
Show map & directions

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Clinical Social Worker (primary) Taxonomy 1041C0700X · Licence 077353-1 (NY)

Record details

NPI number1831480128
Entity typeIndividual (Type 1)
GenderMale
Credentials LCSW
Sole proprietorYes
NPI enumeratedApril 21, 2011
Last updated in NPPESApril 21, 2011

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