Emergency department (ED) visits are common in the United States, with approximately 1 in 5 Americans visiting the ED at least once per year. Older adults, particularly those with Alzheimer’s Disease and Related Dementias (ADRD), use the ED at higher rates and have an even greater risk of adverse outcomes. Crowded ED conditions may pose particular safety risks for those with impaired cognition. Observation unit care has been proposed as a solution to the time-pressured nature of emergency care. Indeed, there has been a marked growth in recent years in the use of observation care for older adults presenting to the ED. Yet, there is concern that observation stays may be inappropriate for some patients and may be associated with poorer outcomes compared to a traditional inpatient stay. Evidence suggests that observation care yields the best outcomes when limited to protocolized care for specific conditions. Yet, the majority of observation care is not provided in such structured settings. Thus, the ideal model of observation care is likely not the predominant one, particularly for the population of patients with Alzheimer’s disease and related dementias (ADRD), who more often present to the ED with nonspecific symptoms and conditions that are less well-defined. Yet, evidence on the modern landscape of observation care for adults with ADRD is lacking. We will use national Medicare claims to examine trends in the utilization and intensity of observation care for Medicare beneficiaries with ADRD. We will use a novel approach to evaluate the degree to which certain hospitals have been substituting observation stays for inpatient care, direct ED discharge or both. Furthermore, we will characterize the trends in clinical outcomes associated with observation care for beneficiaries with ADRD. We will use Medicare claims to identify the patient, hospital and regional-level variables that are associated with these outcomes. We will use the findings from analyses of national Medicare claims to develop a risk-prediction tool for frontline clinicians to risk-stratify beneficiaries with ADRD for adverse outcomes associated with observation care. This national, longitudinal study will enable frontline clinicians to better tailor the use of observation care to the needs of patients with ADRD.