7. Project Summary/Abstract In July 2022, 988 will become the nationwide 3-digit suicide prevention phoneline to access the National Suicide Prevention Lifeline (NSPL). The nationally recognized Zero Suicide (ZS) model has endorsed crisis call centers (CC) and mobile crisis (MC) as key strategies to prevent suicide. Crisis services are also envisioned as a means of increasing access to care for populations that have historically faced barriers to receiving care, including Black/African Americans, people experiencing homelessness, and people living in rural areas. When 988 goes live, the NSPL is expected to expand beyond its current role as a suicide hotline and transform into an entry point for a range of mental health crises as well as a means of dispatching MC teams. However, little is known about what types of calls may come to 988 or what factors will need to be considered to develop best practices in crisis triage decision-making. There is an urgent need to expand the evidence base to inform best practices in CC and MC settings, which are routinely caring for people at high risk of suicide. To fill this gap, this study will leverage a large, comprehensive clinical dataset from Georgia’s statewide crisis system—which is widely regarded as a national leader in crisis services—to characterize CC and MC practices and provide guidance to crisis programs as the US begins to roll out 988. In Aim 1, we will conduct a latent class analysis to quantitatively describe common clinical phenotypes of adults accessing crisis services through a statewide CC between 2016 and 2018 (n=235,762), which can inform what types of crises need to be addressed by 988 call centers. In Aim 2, we will examine sociodemographic, clinical and regional factors that may be associated with referral decisions by Georgia’s CC (n=235,762) and MC (n=34,371), with a particular focus on disparities among groups that historically have poorer access to care. Finally, in Aim 3, we will leverage Georgia’s use of a clinical decision-support tool called the Level of Care Utilization System (LOCUS) to examine cases in which the actual CC referral differs from the most appropriate level of care recommended by the LOCUS, which allows for detection of cases where referral options may be limited. These studies will fill critical gaps in the evidence base to advance our understanding of best practices for suicide prevention in crisis services and will help prepare the US for major crisis system transformations such as 988. The figures presented below are the actual number of mobile crisis visits between 1/1/2016 and 12/31/2018 in the GCAL database.