PROJECT SUMMARY/ABSTRACT Significance: Although system-based efforts within healthcare settings have been heralded as promising for suicide prevention efforts, little is known about how to effectively achieve this. The System of Safety (SOS) represents an unparalleled opportunity to study the implementation of best practice suicide-related care processes that embody the Zero Suicide Essential Elements of Care across emergency departments, inpatient medical and behavioral health units, and primary care clinics associated with a large healthcare system. Investigators: The Project Team has extensive expertise in suicide risk screening, assessment, intervention, and care transition (Boudreaux); implementation science and healthcare systems change (Kiefe); industrial engineering and healthcare continuous quality improvement (CQI) (Pelletier); data science (Mathew); electronic health record (EHR) communication (Cutrona); effectiveness trial design and analysis (Kiefe; Chang); and economic analyses (Rodriguez-Monguio). They are complimented by Co-Investigators and advisors with extensive healthcare systems operations expertise. Combined, the team has over 100 publications related to suicide prevention, systems-change, and effectiveness trial design and analytics. Innovation: In addition to pioneering the implementation of system-wide suicide risk identification and prevention efforts, the SOS will be one of the first to study the prominent CQI strategy called Lean and a novel hub-and-spoke deployment strategy. It will innovate healthcare services research methods by applying novel statistical strategies to analyze data from a stepped wedge cluster randomized design. Approach: This effectiveness trial will use a stepped wedge design across a total of 39 clinical units which will be randomized to a given start time. Aim 1 will measure suicide risk screening (intervention target) and screening's impact on risk identification (patient outcome). Aim 2 will measure the effective implementation of clinician administered interventions, such as safety planning with means restriction counseling (intervention target), on suicide, suicide attempts, and suicide-related acute healthcare (patient outcomes). Exploratory Aims will examine mechanisms of action, moderators, economics, and population effects of the intervention. Environment: With the success of the ED-SAFE and other relevant projects, UMMMHC and UMass Medical School have clearly established their capability of successfully carrying out this study. Impact: This study's innovative approach positions it for a significant impact on the fields of suicide prevention, CQI, and effectiveness trial design and analysis. No other group is better prepared to answer all of the important research questions posed in this proposal. The deliverables will have broad significance across care settings, medical and behavioral populations, and age groups.