Patients admitted to an addiction treatment program are routinely screened for PTSD using a brief self-report survey, the PTSD Checklist (PCL). These forms are collected by clinical staff of the treatment program and scored for PTSD diagnostic criteria. If a patient exceeds threshold criteria (PCL score of greater than or equal to 44) they are approached by a clinical staff member about their potential interest in the study. If they wish to learn more about the study the PI or designee is contacted, a suitable time arranged, and the patient approached for their interest in consenting to the study.