PROJECT SUMMARY Hallucinations are prevalent in the context of a wide variety of mental disorders but also occur in approximately 10% of the general population. Hallucinatory experiences are readily identifiable by those experiencing them, but they are not always indicators of conditions that lead to serious negative outcomes such as hospitalizations, use of emergency services, and suicide attempt. Our risk evaluation capabilities are hampered, in part, by the limitations of our assessment strategies which typically involve resource intensive clinical interviews, administered by trained clinicians, in clinic settings. Ubiquitous smartphone technologies offer us novel opportunities to administer behavioral measures that can capture the experience and impact of hallucinations at a scope, scale, and ecological validity that far exceed clinic-based assessment capabilities. Applying powerful computational methods to the rich data collected using mobile behavioral tasks has the potential to yield tools for identification of those at heightened risk for major clinical and functional impairments. In response to RFA-MH-23-105, we propose to recruit a large sample of people experiencing hallucinations to install a smartphone behavioral measurement package that will prompt them to complete targeted brief self-report measures, audio diaries describing their hallucinatory experiences, and validated audio-administered verbal memory tasks in their own environments. Participants will also complete clinical outcome measures prospectively. Our team will derive data-driven clinical signatures from the mobile behavioral tasks to predict individual differences in severe negative outcomes among people experiencing hallucinations; identify and mitigate inaccuracies in modelling across groups defined by race, sex, and age; examine whether adding smartphone-captured behavioral data to information that is typically available in the clinical record improves model clinical utility; and produ