This research will help identify if a PTSD treatment group, called Cognitive Processing Therapy (CPT), that is used in community settings is helpful in reducing PTSD symptoms among people who are incarcerated. The goal of CPT is to create a space for people to modify unhelpful beliefs related to trauma. A total of 692 participants will be enrolled from 6 locations and can expects to be on study for up to 24 weeks.

The primary objective of this project is to determine the effectiveness of group CPT in reducing conduct reports (violations of prison rules such assaults and substance use), reducing PTSD symptom severity, and address the long-term outcome of recidivism in male and female incarcerated populations.

Up to 692 incarcerated individuals will participate in group assignment. To account for potential participant attribution between consent, group assignment, and the waitlist group receiving treatment, enrollment could be up to 900 participants. AV branch of the study involves a waitlist control group; this group will receive the CPT treatment after the treatment group completes the treatment. Participation in the waitlist control group will not affect participation in any other treatments that are available at the facilities.

Prior to beginning any study procedures, informed consent will be obtained orally and in writing. During the informed consent process, eligible participants will be provided with detailed information about the study, including their right to refuse or discontinue participation at any time and the fact that their decision to participate or decline will have no bearing on their standing within the criminal justice system.

Potential participants will be contacted by calling them over the phone system within the prison. When they arrive to the private testing room, they are asked if they would like to learn about the study and potentially participate. If so, participants undergo consent.

Eligible participants will complete the PCL-5 to ascertain current PTSD symptomology and probable diagnosis. This assessment will take approximately 90 minutes.

Participants will be randomly assigned to the CPT or the waitlist control group. The CPT group will engage in 8 -12, 90-minute treatment sessions (18 hours total). With the optional opportunity to take 15-20 minutes after each session to de-stress and calm down if necessary. These sessions will take place over 6 to 12 weeks, depending on session frequency. CPT group-members are also asked to complete weekly homework (approximately 12 hours total). A maximum of 10 participants, but no less than 3 will be included in each CPT group. When the waitlist control group reaches the treatment phase, if the participant count fall below 3, additional participants will be enrolled to maintain sufficient numbers. Data collection during treatment will mirror that of the active waitlist control group. Participants will be notified via institutional mail which group they have been enrolled in.

In addition to the treatment groups, CPT and control group members will complete a PCL-5 / PHQ-9 at the beginning of each session. As well as pre-treatment testing session prior to the start of treatment. CPT and control group members will complete post-treatment testing within one week after completing week 6 or 12 of treatment. Facilities will have the option to offer one follow up CPT session 6-12 weeks post-treatment. Final follow-up will occur three months after the end of treatment. Procedures will be the same as other timepoint follow-ups. Participants who receive treatment may be selected for a 1on1 interview to hear about their experiences with the group. CPT and control group members will be asked to complete 15-19 sessions in total (pre-treatment, post- treatment, three-month follow-up treatment, 1on1 interview, 12 group sessions and one optional follow-up CPT session).

Participants will be enrolled from the Department of Corrections trauma treatment waitlist who have been screened for:

• No active symptoms of psychosis that would interfere with the individual's ability to participate in the group
• No active suicidal ideation with intent or plan
• Able and willing to participate in group therapy
• 18 years old or older
• meet PCL-5 criteria for current PTSD diagnosis within 2 months of enrollment
• No scheduled release date before the end of the treatment group
• able to understand the consent form as measured by the consent quiz
• have not participated in the previous CPT groups with UW project

The research members performing the assessments will be blind to the group assignment. One study staff will schedule participants according to the randomization, thus minimizing the possibility of systematically biasing the outcome and mediator assessments.