Background: Suicide rates continue to rise across the United States, galvanizing the need for increased suicide prevention and intervention efforts. The Zero Suicide (ZS) model was developed in response to this need and highlights four key clinical functions of high-quality health care for patients at risk of suicide. The goal of this quality improvement study was to understand how six large health care systems operationalized practices to support these functions—identification, engagement, treatment and care transitions. Methods: Using a key informant interview guide and data collection template, researchers who were embedded in each health care system cataloged and summarized current and future practices supporting ZS, including, (1) the function addressed; (2) a description of practice intent and mechanism of intervention; (3) the target patient population and service setting; (4) when/how the practice was (or will be) implemented; and (5) whether/how the practice was documented and/or measured. Normalization process theory (NPT), an implementation evaluation framework, was applied to help understand how ZS had been operationalized in routine clinical practices and, specifically, what ZS practices were described by key informants ( coherence), the current state of norms/conventions supporting these practices ( cognitive participation), how health care teams performed these practices ( collective action), and whether/how practices were measured when they occurred ( reflexive monitoring). Results: The most well-defined and consistently measured ZS practices (current and future) focused on the identification of patients at high risk of suicide. Stakeholders also described numerous engagement and treatment practices, and some practices intended to support care transitions. However, few engagement and transition practices were systematically measured, and few treatment practices were designed specifically for patients at risk of suicide. Conclusions: The findings from this study will support large-scale evaluation of the effectiveness of ZS implementation and inform recommendations for implementation of high-quality suicide-related care in health care systems nationwide. Plain Language Summary Many individuals see a health care provider prior to death by suicide, therefore health care organizations have an important role to play in suicide prevention. The Zero Suicide model is designed to address four key functions of high-quality care for patients at risk of suicide: (1) identification of suicide risk via routine screening/assessment practices, (2) engagement of patients at risk in care, (3) effective treatment, and (4) care transition support, particularly after hospitalizations for suicide attempts. Researchers embedded in six large health care systems, together caring for nearly 11.5 million patients, are evaluating the effectiveness of the Zero Suicide model for suicide prevention. This evaluation focused on understanding how these systems had implemented clinical practices supporting Zero Suicide. Researchers collected qualitative data from providers, administrators, and support staff in each system who were responsible for implementation of practices supporting Zero Suicide. Normalization process theory, an implementation evaluation framework, was applied following data collection to: (A) help researchers catalog all Zero Suicide practices described, (B) describe the norms/conventions supporting these practices, (C) describe how health care teams were performing these practices, and (D) describe how practices were being measured. The findings from this evaluation will be vital for measuring the effectiveness of different Zero Suicide practices. This work will also provide a blueprint to help health care leaders, providers, and other stakeholders “normalize” new and existing suicide prevention practices in their own organizations.