PROJECT SUMMARY/ABSTRACT The period immediately following discharge from acute psychiatric hospitalization is a time fraught with gaps and discontinuities in care for many patients. Despite this time of elevated risk, patients often lack sufficient transitional supports and related resources for returning to the community and resuming long-term outpatient treatment. The long-term goal is to improve the continuity of care for patients with serious mental illness (SMI) by supporting a safer and more efficient bridge from hospital to outpatient care. The objective of this proposal is to test the effectiveness of our empirically-supported, multi-component mHealth intervention called tFOCUS in comparison to enhanced assessment and monitoring to ensure safety and an adequate standard of care (“SAFE”). tFOCUS will be deployed during the high-risk period directly from hospital to outpatient care and provide real-time assessment and intervention to patients via a mobile app, plus user engagement and clinical status updates to clinicians via a web-based “dashboard.” To speed the translation of findings to clinical practice, we will rigorously test the effectiveness of tFOCUS in a fully-powered Hybrid Type 1 Effectiveness-Implementation trial, while collecting information on implementation barriers/facilitators to promote uptake in real world settings. The central hypothesis is that tFOCUS will improve illness self-coping and treatment attitudes, which will lead to reduced: psychiatric symptoms, rehospitalizations, and suicidal ideation/behaviors. tFOCUS will also lead to improved post-discharge treatment engagement and illness recovery. The aims of this proposal are: (1) to conduct a fully-powered, RCT (n=180) to test the effectiveness of treatment-as-usual (TAU) + tFOCUS vs TAU + SAFE; (2) to examine potential mediators and moderators of treatment effects; and, (3) to identify patient, staff, and organizational/system-level factors that may facilitate/hinder tFOCUS implementation. The primary outcome will be overall psychiatric symptoms. The approach is innovative because it is one of the first randomized controlled trials conducted in the U.S. specifically evaluating an mHealth aftercare support program for patients with SMI directly moving from hospital to outpatient care. Also, this study is unique in that it will collect data to generate hypotheses about implementation strategies via a multi-pronged approach involving key stakeholders and additional implementation ata. Upon successful completion of the proposed R01 research, this study will contribute significant actionable data that will lay the groundwork for a large-scale Hybrid Type 3 trial of tFOCUS in diverse hospital settings.