Approximately 25% of combat Veterans with Posttraumatic Stress Disorder (PTSD) seek treatment for traumas that involve potentially morally injurious events (PMIE) rather than danger-based traumas. PMIEs are more strongly associated with functional and psychiatric impairment than life-threat-based combat. Veterans report that PMIEs disrupt their sense of identity and meaning, ability to connect with and trust others, and engender disturbing guilt, shame, rage, and disgust. The sequelae of exposure to PMIEs, otherwise known as moral injury, may explain variance in post-deployment recovery and is a potential unaddressed treatment target. Existing first-line treatments may be limited because they were derived from civilian contexts, poorly fit the war zone context, and do not allow Veterans to discuss the details of the PMIEs with other Veterans. This project will develop a relational dynamic-based group therapy treatment manual that will target functioning and quality of life among Veterans who are impacted by high magnitude PMIEs. The goal of this relational dynamic trauma therapy is to help Veterans identify connections between their current symptoms and their experiences in combat/PMIEs, their current life stressors and relationships, and the historical factors that carry person-specific meaning to their trauma/PMIE. These explorations take place in the presence of attuned and sympathetic others who can resonate to the experience and the affect being expressed. Symptom reduction occurs through increasing the Veteran’s capacity to consciously reflect on their experiences and develop an integrated self-awareness of the various factors that affect their mental states. The result is greater self-reflection, less avoidance, and greater adaptive incorporation of life experiences and their aftermath and meanings into one’s inner world. This CDA-2 will employ innovative user-centered design methods that continuously gather user experiences during treatment development, with the goal of increased effectiveness and usability. User feedback will be synthesized with formative feedback from a clinical expert panel. This objective will be accomplished by pursuing these specific aims: Aim 1: Discover user needs and preferences as well as treatment-engagement barriers and facilitators from the perspectives of PMIE-impacted Veterans and [VA trauma clinicians]. Aim 2: Design a treatment manual and refine it using feedback from Veterans, [trauma clinicians], and an expert clinical advisory board. Aim 3: Conduct two rapid prototyping open trials (i.e., tangibly testing treatment approaches using a prototype manual) with PMIE-impacted Veterans (N = ~12), and iteratively revise the manual based on Veteran, provider, and clinical expert panel feedback, with the following hypothesis: The treatment manual will meet usability, feasibility, learnability, and acceptability criteria.