In the enhanced prolonged exposure condition, participants will complete a CRP instead of a safety plan. The CRP is another recommended standard care practice with suicidal patients that includes many of the same elements as the safety plan (i.e., warning signs, self-management strategies, sources of social support, crisis services), but is created collaboratively by the patient with active input of their clinician rather than being self-guided. The CRP also includes a section focused on the participant's reasons for living, an addition that has been shown to increase positive emotional states (e.g., hope, optimism) and lead to faster reductions in suicidal intent. The CRP will be administered during the first therapy session.

In the standard prolonged exposure condition, participants will complete a safety plan, a procedure that includes personal warning signs for a suicidal crisis, self-management strategies, sources of social support, and contact information for professional resources and crisis services within the participant's local community, as well as the National Suicide Prevention Lifeline phone number. As a recommended standard care practice with suicidal patients, the combination of PE and safety plan represents treatment as usual. The safety plan will be administered during the first therapy session.

PE therapy is a manualized cognitive behavioral therapy consisting of imaginal exposure (repeated recounting of the most disturbing traumatic memory) followed by processing thoughts and feelings related to the imaginal experience; in-vivo exposure (approaching trauma-related situations); psychoeducation about PTSD; and controlled breathing training. Between sessions, participants listen to audio recordings of the imaginal recounting daily and complete in-vivo exercises. Typically, PE is delivered weekly for 10-12, 90-minutes sessions. For this study, participants will complete daily 60-minute sessions for 10 consecutive weekdays during a 2-week period.

19 item self-report assessment of suicidal ideation, range of scores is 0-57, higher score indicates higher suicidal ideation

31 item self-report measure of suicidal thoughts and behavior

20 item self-report measure that assesses the 20 DSM-5 symptoms of PTSD. range is 0-80, higher score indicates higher PTSD symptoms

transdiagnostic measure of current mental health symptomatology. It is an adult measure that consists of 23 questions that assess 13 psychiatric domains, including depression, anger, mania, anxiety, somatic symptoms, suicidal ideation, psychosis, sleep problems, memory, repetitive thoughts and behaviors, dissociation, personality functioning, and substance use.