Psilocybin for Prolonged Grief Disorder

Inclusion Criteria: * Ages 18 years old up to and including 65 years of age * Negative UDS results for illicit drugs at screening and prior to each drug administration session * Consent to all study procedures * Have an existing diagnosis of Prolonged Grief Disorder. May also be determined to have Complicated Grief Disorder without official diagnosis as determined by PI or designate based on DSM V criteria * Score of greater than 25 on the Inventory of Complicated Grief * Agree to abstain from any psychoactive drugs on the day prior to and the day of the drug administration session * People of childbearing potential that are sexually active must agree to continue or initiate practice of a highly effective means of birth control, alone or in combination with another, throughout the study. Highly effective options are: implants, intrauterine devices (IUD), and sterilization. Exclusive use of condoms is not effective. * Be judged by study team clinicians to be at low risk for suicidality as determined by MINI, Columbia Suicide Severity Scale, and the Patient Health Questionnaire-9. * Concurrent psychotherapy or pharmacotherapy with SSRIs, SNRIs, and/or bupropion (\< 300 mg bupropion) is allowed if the type and frequency of the therapy has been stable for at least two months prior to screening and is expected to remain stable during participation in the study * Be otherwise medically stable as determined by screening for medical problems via a personal interview, a medical quest…