Youth with juvenile justice involvement are at markedly increased risk for suicidal ideation, suicidal behavior and death, and non-suicidal self-injury (NSSI) (Gallagher & Dobrin, 2006; Stokes et al., 2015). Much of this suicidal and self-harm behavior occurs in the context of psychiatric and substance use problems and histories of adverse life experiences (e.g., Charak et al., 2019; McNair et al., 2019; Teplin et al., 2015). The rates of mental health disorders and suicide risk increase with more restrictive environments, including juvenile detention facilities (Hayes, 2005; Stokes et al., 2015; Wasserman, et.al., 2010). Given the increased risk of detained youth, the purpose of this study, responsive to NIMH PAR 18-228, “Pilot Studies to Detect and Prevent Suicidal Behavior, Ideation, and Self-Harm in Youth in Contact with the Juvenile Justice System,” is to develop, refine, and preliminarily test a trauma-informed, strengths-based, developmentally appropriate brief intervention for staff in short-term detention facilities responding to detained adolescents’ suicidal ideation and behavior, and NSSI. It is our expectation that this brief intervention will provide support to detained youth through cognitive-behavioral and dialectical behavior therapy strategies focused on increasing youth safety, self-efficacy, reasons for living, and radical acceptance of their current life circumstances. The intervention will be designed to help staff more effectively assess and respond to youth suicidal thoughts and behaviors, and NSSI, resulting in more effective management of youth crises. The intervention will complement and build upon existing resources and assessment and monitoring protocols within the juvenile detention setting. In particular, the intervention will be designed to be delivered on- site at detention facilities by existing detention staff who work with detained youth. The first aim of the project is to develop and refine standard procedures for the new intervention for suicidal youths in crises in juvenile detention. The second aim is to develop procedures for training detention staff members who will provide this intervention to detained youth. In the context of an open trial (n=20), the third aim is to assess the feasibility of this intervention, and to use experiences from implementing the intervention and feedback from detention staff and youth to refine the intervention. The last aim is to obtain, in a pilot randomized controlled trial (n=200), preliminary data regarding the feasibility and acceptability of the intervention, as well as the impact of the intervention on suicidal thoughts and behavior, NSSI, emergency services, linkage to care after release, and presumed mechanisms of action. The proposed research is intended to demonstrate the feasibility and potential utility of a model that can eventually impact services delivery by detention staff for detained at-risk youth, resulting in improved outcomes. The results of this study w...