Abstract: Objective: To assess the feasibility of a family-involved intervention, family support in mental health recovery (FAMILIAR), for veterans with posttraumatic stress disorder (PTSD) seeking psychotherapy at a single Veterans Administration Health System. Method: This mixed-methods study reports qualitative and quantitative findings from a single-group pilot of 24 veterans and their support partners (SPs) about experiences with the intervention and interviews with eight VA mental health clinicians and leaders and the study interventionist to explore intervention feasibility. Findings across data sources were merged within domains of Bowen and colleagues' pilot study feasibility framework. Results: Out of 24 dyads, 16 veterans and 15 associated SPs completed the intervention. Participants viewed the intervention to be valuable and feasible. Veterans and SPs reported that they enrolled in the study to develop a shared understanding of PTSD and treatment. While participants identified few logistical barriers, finding a time for conjoint sessions could be a challenge. Veterans, SPs, and providers discussed benefits of the intervention, including that it facilitated conversation between the veteran and SP about PTSD and mental health care and helped to prepare the dyad for treatment. Providers noted potential challenges integrating family-involved interventions into clinical workflow in VA and suggested the need for additional training and standardized procedures for family-centered care. Conclusions: Our study identified potential implementation facilitators (e.g., standard operating procedures about session documentation, confidentiality, and family ethics) and challenges (e.g., clinical workflow integration) that require further study to bring FAMILIAR into routine clinical care.