Suicide rates are rising in the US and more than a million Americans try to take their own lives each year. Effective, brief, low-cost interventions for individuals who attempt suicide are essential to saving lives and achieving the goals of the National Strategy for Suicide Prevention. This proposal takes advantage of a time- sensitive research opportunity to test the effectiveness of the Attempted Suicide Short Intervention Program (ASSIP), a manualized 3-session intervention for recent suicide attempt survivors that produced dramatic reductions in suicide attempts in a efficacy trial–80% fewer reattempts and an average of 72% fewer hospital days over 24 months in the intervention group compared to controls. Our research will now test its effectiveness of in the US public mental health care system, examine theoretically grounded mechanisms, and explore cost-effectiveness. ASSIP is currently being implemented by New York State in a Zero Suicide initiative funded by SAMHSA. Consistent with NIMH Notice of Interest MH-17-031, our project leverages this federal investment and a strong state partnership to conduct effectiveness research. Our project has three aims: Aim 1. Effectiveness. The primary aim of this study is to determine the effectiveness of ASSIP in reducing suicide reattempts in a community mental health setting in the U.S. To accomplish this aim we will conduct a randomized controlled trial with 400 individuals referred from psychiatric inpatient and emergency services following a suicide attempt. Participants will be randomized to receive either usual care + ASSIP (intervention arm) or usual care only (control arm), and followed for assessments at baseline, 3, 6, 12, and 18 months. Aim 2. Mechanism. The secondary aim of this study to examine the psychological mechanisms of ASSIP as predicted by the Interpersonal Theory of Suicide. We will conduct statistical analyses of a mediation model to determine (a) whether ASSIP improves perceptions of low belonging and being a burden on others, and (b) whether the effect of treatment on reductions in suicide re-attempts is mediated by these improvements. Aim 3. Cost-Effectiveness. The exploratory aim of this study is to estimate, from the perspective of an ASSIP provider, the incremental cost per suicide attempt averted by delivering ASSIP to supplement usual care following a suicide attempt. We will gather pre-implementation accounting data, personnel time logs, and 12- month medical record reports of emergency and inpatient psychiatric visits. We will use these data together with effectiveness results to calculate the incremental cost-effectiveness ratio (ICER). This time-sensitive study builds effectiveness research into a federally-funded Zero Suicide grant to New York state, consistent with a specific request from NIMH for such applications. If hypotheses are supported, the study will provide evidence of a brief, practical, and novel therapy that reduces suicide reattempts in a real-world h...