1. ability to understand and sign informed consent

2. ability to write in English;

3. age between 18-55 (average age of menopause in the US)

4. \[women only\] naturally cycling (i.e., regular cycles, not on gonadal-related hormones)

5. current diagnosis of a moderate or severe DSM-5 SUD

6. current diagnosis of DSM-5 PTSD

7. sufficient memory of the trauma to write about the event

8. at least 5 business days left in their residential treatment episode (to allow for 5 treatment sessions).

Mechanisms of Written Exposure Therapy in Residential SUD Treatment