If you have mental health providers, they are often the most helpful resources for finding and vetting programs that suit your specific mental health needs.
Recovery.com is an extensive directory of treatment programs that is filterable by location, therapeutic approach, level of care, and more.
NAMI Affiliate: contact an affiliate at your local National Alliance on Mental Illness for free guidance with finding partial hospitalization programs.
FindTreatment.gov: a comprehensive website for locating partial hospitalization programs near you.