The purpose of this study is to culturally adapt a brief psychological intervention for Post-Traumatic Stress Disorder (PTSD) and assess its efficacy, feasibility, and acceptability in a pilot trial. The intervention has been shown to be efficacious among individuals with comorbid severe mental illness (SMI) and PTSD. The study will be conducted in three phases. The first phase will determine a description of trauma and responses to traumatic experiences among patients with severe mental illness. The first phase of the study will also determine participants' and mental health care providers' perceptions of suitable PTSD interventions in this middle-income context. The findings will then be used to culturally adapt the brief intervention in the second phase. A pilot trial will be conducted in the third phase of the study. Participants with comorbid SMI and PTSD will be randomized into two groups (n= 20 intervention group, n= 20 control group). Outcomes of the intervention such as the severity of PTSD symptoms, knowledge about PTSD will be assessed at baseline and at different timelines during the study. This study will fill the knowledge gap on trauma and its consequences among individuals with severe mental illness in Botswana, it will also contribute to the improvement of clinical practice in the management of PTSD and SMI.