Study of Feasibility and Safety of MDMA-Assisted Group Therapy for the Treatment of PTSD in Veterans

Inclusion Criteria: * Are at least 18 years old. * Are a U.S. Military Veteran * Are fluent in speaking and reading the predominantly used or recognized language of the study site. * Are able to swallow pills. * Agree to have study visits recorded, including Experimental Sessions, outcome assessments, and non-drug psychotherapy sessions. * Must provide a contact 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 able to become pregnant, must have a negative pregnancy test at study entry and prior to each Experimental Session, and must agree to use adequate contraception through 10 days after the last Experimental Session. * Must not participate in any other interventional clinical trials during the duration of the study. * Have a current PTSD diagnosis at the time of screening. Exclusion Criteria: * Are not able to give adequate informed consent. * Have uncontrolled hypertension. * Have a marked baseline QTcF interval \>450 milliseconds \[ms\] demonstrated on repeated ECG assessments. * 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 or biliary disease. * Have history of hyponatremia or hyperthermia. * Weigh less than 48 kilograms (kg). * Are pregnant or nursing, or are able to become pregnant and are not practicing an effective means of birth control. * Have an active illicit drug or prescription drug substance use disorder