PROJECT SUMMARY Millions of Americans living with serious illness experience burdensome symptoms and receive aggressive care that is not aligned with their goals and preferences. A growing body of evidence suggests that palliative care, which entails a supportive approach to care focused on maximizing quality of life, improves patient- centered, clinical, and economic outcomes. For this reason, national guidelines recommend that clinicians either provide palliative care themselves (primary) or consult experts (specialist) as part of standard serious illness care. For these reasons, most hospitals in the U.S. have invested in specialist palliative care programs. Yet, palliative care delivery remains insufficient among patients with serious illness, particularly those with advanced Alzheimer's Disease and Related Dementias (ADRD), and use of specialist palliative care services is often inefficient and inequitable, largely due to clinicians' difficulty identifying which patients are most likely to benefit from them. Many hospitals have begun to implement prognostic triggers in the electronic health record (EHR) to facilitate more reliable and equitable patient identification, however, none have been rigorously tested for their effects on patient-centered outcomes. Furthermore, palliative care triggers cannot solely rely on the limited workforce of palliative care specialists, but rather approaches that promote primary and specialist palliative care are needed, yet evidence is lacking for how to optimally do so. The main objective of this study is to evaluate a strategy that combines an EHR-based prognostic-trigger with two effective clinician-directed nudges to provide either primary or specialist palliative care for seriously ill hospitalized patients. Specifically, the behavioral intervention involves a simple EHR alert to the primary clinicians caring for identified patients that requires them to actively choose whether or not to provide primary palliative care, and only if they decline, a default order for specialist palliative care is entered from which they can opt-out. We will conduct a hybrid type 1 pragmatic, cluster randomized trial among nearly 7,000 patients across 6 diverse hospitals to study the intervention's effectiveness on hospital-free days and numerous other patient-centered, clinical, and economic outcomes. We will also conduct an embedded mixed methods study to understand clinician and hospital contextual factors that influence the intervention's uptake. Finally, we will evaluate for treatment effect heterogeneity among patients with ADRD and other pre-specified subgroups to determine which types of patients derive the greatest benefit from a systematic approach to nudge palliative care. This study will provide high-quality evidence regarding the effectiveness of a scalable and sustainable approach to promote collaborative primary and specialist palliative care among a large and diverse patient cohort, will advance the science ...