Background: Katherine Hoerster, PhD, MPH is a staff psychologist with VA Puget Sound-Seattle (VAPS) and Acting Assistant Professor with the University of Washington (UW) Department of Psychiatry and Behavioral Sciences. Dr. Hoerster has demonstrated a commitment to conducting VA research focused on improving the health and well-being of Veterans with PTSD. The proposed career development award (CDA-2) will ensure that Dr. Hoerster will develop the skills and expertise necessary to become an independent health services researcher dedicated to improving care for Veterans with psychiatric illness. Career Development Plan: The proposed CDA-2 is focused on studying a peer-led behavioral weight management intervention that augments VA's existing weight management program (MOVE!) for Veterans with PTSD: MOVE!+UP (Improving MOVE! for Veterans with PTSD Using Peer Support). MOVE!+UP will be delivered by a paid peer support counselor in 4 group sessions in the first month of MOVE!, and will involve learning basic anxiety management skills and engaging in community-based physical activity to address barriers (e.g., hypervigilance). Four biweekly brief telephone counseling sessions will take place after MOVE!+UP's group ends and will focus on maintaining gains and problem-solving barriers. This intervention is proposed because Veterans with PTSD experience 1) high rates of obesity and related conditions due to inactivity and unhealthy diet; 2) reduced effectiveness of MOVE!; and 3) unique barriers to physical activity and healthy diet. Social support buffers these barriers to physical activity and healthy diet for Veterans with PTSD, and Veterans with PTSD endorse a strong preference for working with peers on these issues. In addition to the potential health behavior and weight loss benefits, MOVE!+UP is also expected to address PTSD symptoms. The proposed CDA-2 involves two studies that will assess MOVE!+UP's acceptability and feasibility and guide its refinement: 1) an uncontrolled pilot trial and follow-up qualitative interviews among 28 obese Veterans with PTSD; and 2) qualitative interviews with a purposive sample of 12-16 VA providers and key stakeholders. The refined MOVE!+UP intervention will be tested in a randomized controlled trial (RCT) to determine whether MOVE!+UP leads to better weight loss than usual care MOVE! among 336 obese Veterans with PTSD. Dr. Hoerster will conduct the research and training under mentors and consultants expert in peer support and behavioral weight loss interventions (Karin Nelson, MD, MSHS), health behavior intervention RCTs (Gayle Reiber, PhD, MPH) and specifically those for Veterans with PTSD (Miles McFall, PhD), integrated care and implementation science (J?rgen Un?tzer, MD, MPH, MA), physical activity and dietary assessment and intervention (Brian Saelens, PhD), and qualitative (Helene Starks, PhD, MPH) and statistical (Dr. David Atkins, PhD) methods. Mentors and consultants are located at VAPS or UW. Dr. Hoerster will also participate in UW coursework, local and national trainings, national collaborations, and other academic and professional activities to support training goals. The CDA-2 research and training plan will provide essential preparation to advance Dr. Hoerster's independent research career in the following areas: 1) peer support approaches to promoting physical activity and diet; 2) interventions to address chronic disease in Veterans with psychiatric conditions; 3) RCTs for behavioral interventions; and 4) dissemination and implementation of behavioral interventions. Impact: This CDA-2 will accelerate Dr. Hoerster's independence as a VA health services investigator. Dr. Hoerster will focus on studying ways to reduce inequitable disease burden for Veterans with psychiatric conditions and use this research to shape VA mental health services delivery.