The Effects of Psilocybin-Facilitated Experience on the Psychology and Effectiveness of Religious Professionals

Inclusion Criteria: * Inclusion criteria for religious professionals: * 25 to 76 years old * Have given written informed consent * College graduation or equivalent and graduate/professional training. * Recognized leadership position in a well-established religious organization; professional activities must include significant time interacting with those seeking religious/spiritual guidance or support. * During the next two years there is no foreseen likelihood for a major potentially life-altering event for her or himself or a close family member (e.g. retirement or major career change for the volunteer; life-threatening illness of a spouse or child of the volunteer) * Agree to consume approximately the same amount of caffeine-containing beverage (e.g., coffee, tea) that he/she consumes on a usual morning, before arriving at the research unit on the mornings of psilocybin session days. If the participant does not routinely consume caffeinated beverages, he/she must agree not to do so on session days. * Agree to refrain from using any psychoactive drugs, including alcoholic beverages and nicotine, 24 hours before and after each drug administration. The exception is caffeine. Participants will be required to be either a non-smoker or a non-daily smoker. * Agree not to take any PRN medications on the mornings of drug sessions * Agree not to take sildenafil (Viagra®), tadalafil, or similar medications within 72 hours of each drug administration. * Agree that for one week before each drug session, he/she will refrain from taking any nonprescription medication, nutritional supplement, or herbal supplement except when approved by the study investigators. Exceptions will be evaluated by the study investigators and will include acetaminophen, non-steroidal anti-inflammatory drugs, and common doses of vitamins and minerals. * Have no or limited lifetime use of hallucinogens. Preference will be given to enrolling volunteers with no prior use. If we decide to enroll a volunteer with prior use, preference will be given for those who report the fewest exposures or the least enduring effects from such use. Exclusion Criteria: * General medical exclusion criteria for religious professionals: * Women who are pregnant (as indicated by a positive urine pregnancy test assessed at intake and before each drug session) or nursing; women who are of child-bearing potential and sexually active who are not practicing an effective means of birth control. * Cardiovascular conditions: coronary artery disease, stroke, angina, uncontrolled hypertension, a clinically significant ECG abnormality (e.g., symptomatic atrial fibrilation), or TIA in the past year * Epilepsy with history of seizures * Insulin-dependent diabetes; if taking oral hypoglycemic agent, then no history of hypoglycemia * Currently taking psychoactive prescription medication on a regular (e.g., daily) basis * Currently taking on a regular (e.g., daily) basis any medications having a primary centrally-acting pharmacological effect on serotonin neurons or medications that are MAO inhibitors. For individuals who have intermittent or PRN use of such medications, psilocybin sessions will not be conducted until at least 5 half-lives of the agent have elapsed after the last dose. * More than 20% outside the upper or lower range of ideal body weight according to Metropolitan Life height and weight table Psychiatric Exclusion Criteria for religious professionals: * Current or past history of meeting DSM-5 criteria for Schizophrenia, Psychotic Disorder (unless substance-induced or due to a medical condition), or Bipolar I or II Disorder * Current or past history within the last 5 years of meeting DSM-5 criteria for alcohol or substance use disorder (excluding caffeine and nicotine) or severe major depression * Have a first or second-degree relative with Schizophrenia, Psychotic Disorder (unless substance induced or due to a medical condition), or Bipolar I or II Disorder * Has a psychiatric condition judged to be incompatible with establishment of rapport or safe exposure to psilocybin * History of violent or suicidal behavior * Family history of completed suicide