Background: Over 1 million Veterans have PTSD and most (80% or more) do not receive first-line treatments, evidence-based psychotherapies, despite significant VA investment to increase access to these treatments. Clinicians often struggle to engage Veterans in evidence-based psychotherapies because they can be emotionally challenging treatments. Engagement could be catalyzed by mental health providers integrated into primary care (i.e., VA’s Primary Care-Mental Health Integration, or PC-MHI) to maximize the reach of engagement efforts beyond specialty PTSD settings. Shared decision making, a process by which the patient and provider discuss treatment options, weigh benefits and risks, and select a treatment that meets the patient’s needs, addresses known patient and provider barriers to evidence-based psychotherapies, including knowledge, self-efficacy, and trust. However, no study has examined shared decision making for PTSD in primary care. The proposal will address this knowledge gap by developing and refining a shared decision making intervention for PTSD, Patient Readiness for Improvement through Motivation, Engagement, and Decision-making (PRIMED), using input from Veterans with diverse perspectives, PC-MHI providers, and VA operational partners to optimize integration of shared decision making into clinical care. We will collect acceptability and feasibility data to support an application for a future effectiveness-implementation trial. Significance/Impact: Dr. Chen’s proposed research addresses three HSR&D and VA priorities: 1) increase engagement and retention of Veterans in evidence-based PTSD treatments, 2) advance health services research methods, specifically implementation science and user-centered design, which focuses on thorough integration of Veteran and frontline provider input, and 3) support suicide prevention efforts through effective treatment of PTSD, a major risk factor for suicide. Innovation: The proposed project will promote significant change in current VA clinical practice. PC-MHI providers typically refer out patients with PTSD and defer discussions about treatment options to specialty providers. This proposal will help PC-MHI providers use a formal engagement strategy, shared decision making, to improve patients’ knowledge of first-line PTSD treatments and to build motivation for care. Specific Aims: 1) Refine PRIMED using user-centered design methods and diverse Veterans’ perspectives, 2) Beta test PRIMED in one rural and one urban PC-MHI clinic to optimize integration into clinical workflow and achieve satisfactory acceptability and feasibility across a range of settings, 3) Conduct a small, randomized pilot trial (N=40) of PRIMED vs. usual care in two VA PC-MHI clinics to assess the feasibility of study procedures, which will inform a future larger trial. Methodology: In Aim 1, Dr. Chen will conduct qualitative interviews using user-centered design methods with 25 VA PC-MHI patients with PTSD, oversampling women...