Participants first receive placebo at their first session in the laboratory. Then will return to the laboratory 5 days later and will receive 125 mg MDMA. Finally, 5 days later will return to the laboratory and will receive 20 mg of MA.

Participants first receive 125 mg of MDMA at their first session in the laboratory. Then will return to the laboratory 5 days later and will receive placebo. Finally, 5 days later will return to the laboratory and will receive 20 mg of MA.

Participants first receive 20 mg of MA at their first session in the laboratory. Then will return to the laboratory 5 days later and will receive placebo. Finally, 5 days later will return to the laboratory and will receive 125 mg of MDMA.

Participants will be given 125 mg of MDMA.

The POMS measures individuals' mood states. This is a validated scale to measure positive and negative mood states. The POMS contains 30 items and assesses six identified mood factors: Tension-Anxiety, Depression-Ejection, Anger- Hostility, Vigor-Activity, Fatigue-Inertia, and Confusion-Bewilderment. Scoring of the instrument provides a global score of 0 to 120 or individual domain scores. Lower scores indicate better mood state. The POMS brief form is a simple self-rating instrument.