PROJECT SUMMARY Heart failure (HF) is the leading cause of hospitalization in adults aged 65 and older. More than 3 million hospitalizations occur each year in older adults with HF and recurrent hospitalizations after discharge are common, costly, and often preventable. For more than a decade, 30-day hospital readmissions have received considerable attention as an actionable target to improve quality of care and reduce costs in the older-adult (Medicare) population. Despite these investments, high rates of (re)hospitalization continue to put enormous strain on the U.S. healthcare system and on those suffering from the disease. We argue that these strategies have been largely ineffective because they focus on a single snapshot of a patient’s risk of hospitalization (30- day readmission) and do not consider the majority of hospitalizations that occur over the course of the illness. Therefore, efforts to predict and ultimately lower hospital readmissions in older adults will continue to fall short until the full progession of hospitalizations are recognized and addressed. In response to this urgent need, our study will address three critically unanswered questions: What are the most common patterns of hospitalization that occur in older adults diagnosed with HF? Who are the patients most likely to follow these patterns of hospitalization? And what are the factors that can help prevent hospitalizations during the course of treatment? Drawing from a life course perspective and using data from a nationally-representative longitudinal study of older adults, Medicare claims, and electronic health records, our proposed aims are threefold: First, we will classify the major trajectories of hospitalization that occur in older adults diagnosed with HF. This aim will provide evidence of how the number and timing of hospitalizations vary among HF patients over the course of their illness. Second, we will examine how a wide array of demographic, socioeconomic, psychosocial, behavioral, health-, and hospital-related factors are associated with patterns of hospitalization in HF patients. This aim will allow us to determine key patient characteristics that can be assessed at the time of diagnosis to predict a person’s probability of having a given trajectory of admissions over the course of their illness. Third, we will identify factors that may reduce hospitalizations during the course of HF treatment. Our final aim will examine a similarly wide range of factors that may alter the course of a trajectory (i.e., timing and/or number) of hospitalizations, particularly among patients who experience high numbers of hospitalizations and/or face critical periods of risk. Bringing together a strong team of interdisciplinary investigators, the results from this project will have enormous potential to inform the design, targeting, and timing of interventions that are most likely to succeed in reducing the significant burden of hospitalizations in older adults.