Trauma-related guilt is common and impairing among trauma survivors, particularly among treatment seeking Veterans with posttraumatic stress disorder (PTSD). Guilt is a distressing emotion that arises when trauma survivors blame themselves for the outcome of a traumatic event and guilt turns to shame when people judge not just their actions but themselves negatively because of what happened. Guilt is positively associated with severity of PTSD and depression symptoms, suicidal ideation, poorer psychosocial functioning, and shame. Among those with PTSD, guilt is one of the symptoms likely to persist after PTSD treatment, suggesting further intervention targeting guilt is needed. Although evidence-based trauma-focused PTSD treatments such as Cognitive Processing Therapy (CPT) are effective to treat PTSD and trauma-related guilt, many still experience symptoms or maintain their diagnosis after treatment, and dropout from these generally 12+ session protocols is high. Veterans show lower response and higher dropout than others with PTSD. Delivering protocols that are generally 12 or more sessions challenges the Veterans Affairs (VA) healthcare system given high demand for mental health care. For these reasons, additional and less burdensome approaches are needed. Brief treatment that targets mechanisms that are distressing and associated with multiple problems and disorders may be an understudied but promising way to treat PTSD and other posttraumatic psychopathology. Our work shows that a brief treatment targeting trauma-related guilt and shame, Trauma Informed Guilt Reduction Therapy (TrIGR), can reduce guilt, PTSD, depression, and distress among Veterans and help them reengage with activities they find meaningful. In a preliminary efficacy study with 144 OEF/OIF/OND Veterans with guilt from a deployment trauma, we found large effects in PTSD symptom reduction and moderate effects in depression symptom reduction in TrIGR compared to supportive therapy. More than 50% lost their PTSD diagnosis and two thirds showed clinically meaningful change. Dropout was low and attendance was high - Veterans attended more than five of six sessions on average. Whether TrIGR is no less effective than longer, more resource heavy evidence-based PTSD treatments disseminated across by VA, like CPT, is the next critical question. The proposed randomized clinical trial (RCT) will be the first non-inferiority trial of TrIGR and the first to compare TrIGR to a first tier PTSD treatment, specifically CPT. It will also be the first to evaluate TrIGR with Veterans from all eras with guilt from any type of traumas, as our previous work was exclusively with Veterans of the conflicts in Iraq and Afghanistan with deployment-related traumas. 158 Veterans across two VA sites will be randomized to TrIGR or CPT. Exclusion criteria will be minimal so that generalizability will be high. Treatment will be delivered in VA mental health clinics. The primary aim is to evaluate if TrIGR is n...