MDMA-Assisted Psychotherapy for Anxiety Associated With a Life-Threatening Illness

Inclusion Criteria: * Diagnosed with life-threatening cancer or non-dementing neurological illness, which can be ongoing or in remission, but with a possibility of recurrence * Prognosis of at least nine months life expectancy from the time of screening * Have anxiety as a result of facing their illness * Are at least 18 years old * Are willing to refrain from taking any psychiatric medications during the study period; * Are willing to commit to medication dosing, experimental sessions, follow-up sessions, and to complete evaluation instruments * Are willing to remain overnight at the study site after each experimental session until after the integrative session occurring the next morning * Must sign a medical release for the investigators to communicate directly with their therapist and doctors; * Are willing to select up to three observers who will complete observer measures of subject attitudes and behavior * Negative pregnancy test if able to bear children and agree to use effective birth control * Are proficient in speaking and reading English * Agree to have all psychotherapy sessions recorded to audio/video. Exclusion Criteria: * Are pregnant or nursing, or if a woman who can have children, those who are not practicing an effective means of birth control; * Weigh less than 48 kg * Are abusing illegal drugs * Are unable to give adequate informed consent * Upon review of past, current drugs/medication must not be on or have taken a medication that is exclusionary * Upon review of medical or psychiatric history must not have any current or past diagnosis that would be considered a risk to participation in the study * Have used "Ecstasy" (material represented as containing MDMA) at least once within twelve months of enrollment.