Inclusion Criteria:  Meet criteria for PTSD Are at least 18 years old Are a resident of Ontario and live within 200km of the study site Are in good physical health Are proficient in speaking and reading English Are willing to have all visits audio and video recorded Are able to swallow pills Agree to all study rules and commit to all medical and therapy visits If in psychotherapy, are willing to allow the study therapists to communicate directly with your therapist Are willing to stop taking psychiatric medications, herbal supplements, prescription and nonprescription medications during the study Agree not to drive for at least 24 hours after taking MDMA Agree to stay overnight on two separate occasions after each full-day MDMA-Assisted Psychotherapy Session Are not pregnant and will commit to not becoming pregnant during the study, if you are able to become pregnant Have a supportive relative, spouse, close friend or other caregiver who can serve as your emergency contact Agree to inform the researchers within 48 hours of any medical conditions and procedures Agree to not participate in any other clinical trials during this study  Exclusion Criteria:  Are pregnant or could become pregnant and not using birth control Have a history of, or a current psychotic disorder, bipolar 1 disorder or dissociative identity disorder Have a history of a medical condition that could make receiving MDMA unsafe (e.g. glaucoma, heart attack, stroke, aneurysm) Have a history of Diabetes Mellitus (Type 2) that a doctor determines is not stable Have hypothyroidism (low activity in the thyroid gland) and are not on thyroid replacement Have high blood pressure, a history of heart disease, heart failure, irregular activity in the heart or require heart medication Have liver disease with symptoms Have history of hyponatremia (when you have decreased levels of sodium in the blood, which can cause confusion, seizures, fatigue and low levels of consciousness) Have history of hyperthermia (when you have a dangerously overheated body, usually in response to hot, humid weather) Weigh less than 48 kg Have recently engaged in suicidal behavior or had serious suicidal thoughts (this will be assessed by a therapist) Require ongoing therapy with a psychiatric medication Have a current eating disorder with active purging Have current major depressive disorder with psychotic features Are a serious risk to others Have recently received Electroconvulsive Therapy (ECT) Have recently engaged in ketamine-assisted therapy or used ketamine Have current substance use disorder (not including caffeine or nicotine) Have recently used "Ecstasy" (material represented as containing MDMA) Are not able to give adequate informed consent Are not able to adhere to the requirements for procedures, attendance and timing of visits, and observe limits regarding study staff time and support as indicated by a time-limited clinical trial Are currently engaged in compensation litigation whereby financial gain would be achieved from prolonged symptoms of PTSD or any other psychiatric disorders