Background: Suicide is a major public health concern, particularly among Veterans with serious mental illness (SMI, i.e., psychotic disorders or bipolar disorders). These Veterans have among the highest rates of suicidal ideation and behavior among U.S. and Veteran populations. Yet, an SMI diagnosis is often an exclusion criterion for suicide-focused clinical trials, and people with SMI are frequently disengaged from care, have cognitive impairments, and have limited social supports. These factors may likely impact the feasibility and usefulness of current suicide prevention interventions such as suicide safety planning – a VHA standard of care. This proposal refines and pilots SUicide Prevention by Peers Offering Recovery Tactics (SUPPORT) – the first suicide prevention intervention tailored to Veterans with SMI to improve participation in their lives and society. Significance/Innovation: Suicide prevention is a top clinical priority for VA/DoD and RR&D. This research is innovative for several reasons: 1) SMI diagnoses have frequently been excluded from suicide prevention research and this proposal seeks to tailor a novel suicide-focused intervention specifically to Veterans with SMI; 2) this proposal is one of few studies that includes Veterans with SMI to enhance safety planning, which is crucial given that it is an existing suicide prevention standard of care in VHA; 3) this proposal integrates the recovery model and best practices into suicide prevention; 4) SUPPORT is delivered by Peer Specialists, which the 2019 VA/DoD Clinical Practice Guidelines for the Assessment and Management of Patients at Risk for Suicide highlighted a priority for future research to explore “post-acute care approaches,” such as safety planning, and that such approaches could be peer-delivered; 5) this is the first intervention to integrate cognitive learning strategies in a suicide-focused intervention to accommodate cognitive impairments in SMI. Methodology: The proposed 5-year study aims to refine and pilot a peer-delivered intervention to improve functional and social recovery to decrease suicide risk; the proposal consists of two phases. Phase 1 (1.5 years) employs a user-centered design approach to refine SUPPORT aided by scientific and consumer (n=8) advisory board stakeholders as well as training our PSs to fidelity on pilot cases in an open trial (n=15) and qualitative interviews. SUPPORT is a 4-week peer-delivered intervention intended to augment safety planning by addressing functional and social goals personalized to each Veteran’s recovery following a suicidal crisis while including cognitive learning strategies to enhance recall and salience of intervention material. Following adaptations from Phase 1, Phase 2 (3.5 years) includes a pilot (n=50) randomized controlled trial (RCT) of SUPPORT compared to an enhanced standard care (ESC) condition that contains the elements of standard practice suicide prevention delivered at VHA, which include: 1) suicide ...