Inclusion Criteria:  Determined, based upon medical and social work evaluation, to require inpatient psychiatric admission without further need for medical diagnostic evaluation and treatment. Treatment-resistant depression (defined as failure of response to trials of at least 2 antidepressant courses, each of at least 4 weeks' duration) Parent/guardian available for consent (in person or by phone)  Exclusion Criteria:  Any of the following co-existing diagnoses: primary psychotic disorder (schizophrenia, schizoaffective) autism spectrum disorder, developmental delay/intellectual disability, substance abuse disorder within the last 6 months Aggressive behavior, homicidal ideation Altered mental status Pregnancy or breastfeeding, Currently receiving (or receipt within last 24 hours) medication acting on NMDA receptor system (lamotrigine, dextromethorphan, methadone, clarithromycin, amantadine) Incomplete medical evaluation or stabilization Contraindications to or anaphylaxis or prior adverse reaction to Ketamine No caregiver available In custody of a law enforcement agency