Psilocybin and Spiritual Practice

Eligibility criteria for volunteers who will receive psilocybin Inclusion Criteria: * 21 to 70 years old * Have given written informed consent * Have a high school level of education * Be healthy and psychologically stable as determined by screening for medical and psychiatric problems via a personal interview, a medical questionnaire, a physical examination, an electrocardiogram (ECG), and routine medical blood and urinalysis laboratory tests. * Have an active interest in exploring and developing their spiritual lives * Cigarette smokers must agree to abstain from smoking on psilocybin session days from 1 hour before psilocybin administration until at least 6 hours after psilocybin administration. * 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 drug session days. If the volunteer does not routinely consume caffeinated beverages, he or she must agree not to do so on session days. * Agree to refrain from using any psychoactive drugs, including alcoholic beverages, within 24 hours of each psilocybin administration. Exceptions include caffeine and nicotine. * Agree not to take any PRN medications on the mornings of psilocybin sessions * Agree that for one week before each psilocybin 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. Exclusion Criteria: General medical exclusion criteria: * 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., atrial fibrillation), 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 Psychiatric Exclusion Criteria: * Current or past history of meeting DSM-IV 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-IV criteria for alcohol or drug dependence (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. * Currently meets DSM-IV criteria for Anorexia Nervosa, Bulimia Nervosa, or other psychiatric conditions judged to be incompatible with establishment of rapport or safe exposure to psilocybin