A Study of Psilocybin for Major Depressive Disorder (MDD)

Inclusion Criteria: * 21 to 65 years old * Able to swallow capsules * If of childbearing potential, agree to practice an effective means of birth control throughout the duration of the study * Have an identified support person and agree to be accompanied home by that person following dosing * Have sustained moderate-severe depression symptoms at Screening and Baseline * Meet DSM-5 criteria for a diagnosis of major depressive disorder and are currently experiencing a major depressive episode of at least a 60-day duration at the time of screening Exclusion Criteria: * Women who are pregnant or who intend to become pregnant during the study or who are currently nursing * Have any of the following cardiovascular conditions: uncontrolled hypertension, coronary artery disease, congenital long QT syndrome, cardiac hypertrophy, cardiac ischemia, congestive heart failure, myocardial infarction, tachycardia, artificial heart valve, a clinically significant screening ECG abnormality, or any other significant cardiovascular condition * Have a history of stroke or Transient Ischemic Attack (TIA) * Have moderate to severe hepatic impairment * Have epilepsy * Have insulin-dependent diabetes * Have a positive urine drug test * Nicotine dependence that would disallow an individual to be nicotine free for the 7-10 hours during the dosing period * Meet DSM-5 criteria for schizophrenia spectrum or other psychotic disorders, including major depressive disorder with psychotic features, or Bipolar I or Bipolar II Disorder * Meet DSM-5 criteria for antisocial personality disorder * Meet DSM-5 criteria for a moderate or severe alcohol or drug use disorder