Study of Safety and Effects of MDMA-assisted Therapy for Treatment of PTSD

Inclusion Criteria: * Are at least 18 years old. * Are fluent in speaking and reading a recognized language of the study site. * Are able to swallow pills. * Agree to have study visits recorded, including Study Drug Sessions and non-drug therapy sessions. * Must provide a contact (relative, spouse, close friend, or other support person) who is willing and able to be reached by the investigators in the event of a participant becoming suicidal or unreachable. * Must agree to inform the investigators within 48 hours of any medical conditions and procedures. * If of childbearing potential, must have a negative pregnancy test at study entry and prior to each Experimental Session, and must agree to use adequate birth control through 10 days after the last Experimental Session. * Must not participate in any other interventional clinical trials during the duration of the study, and commit to medication dosing, therapy, and study procedures. * At baseline, have moderate PTSD diagnosis. Exclusion Criteria: * Are not able to give adequate informed consent. * Have uncontrolled hypertension. * Have a marked baseline prolongation of QT/QTc interval (e.g., repeated demonstration of a QTc interval \>450 milliseconds \[ms\] in males and\>460 ms in females corrected by Friderica's formula). * Have a history of additional risk factors for Torsade de pointes (e.g., heart failure, hypokalemia, family history of Long QT Syndrome). * Have evidence or history of significant medical disorders. * Have symptomatic liver disease. * Have history of hyponatremia or hyperthermia. * Weigh less than 48 kilograms (kg). * Are pregnant or nursing, or are of childbearing potential and are not practicing an effective means of birth control. * Have current alcohol or substance use disorders.