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 MDMA 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.
• * Must commit to medication dosing, therapy, and study procedures.
• * 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.
• * Are abusing illegal drugs or alcohol.