Abstract Patients who are racial and ethnic minorities share excessive burden of disease and worse outcomes for critical illness. Black patients in particular are not only at higher risk of developing diseases such as acute respiratory failure (ARF) and sepsis, but also at increased risk of mortality. Patients with ARF or sepsis generally receive medical care in either the intensive care unit (ICU) or the general medicine ward. Typically, most would believe that the decision for triage location would only be based on illness severity. However, hospital level factors may influence triage decisions. Capacity strain, defined as a limitation in a care unit's ability to deliver high-quality care to patients due to resources, has been associated with healthcare decision making. Capacity strain is an important systems phenomenon because it is (1) common to all acute healthcare systems, (2) readily perceivable by healthcare providers, and (3) associated with poor clinical outcomes. Despite growing literature demonstrating the role of capacity strain in healthcare operations, no previous study has been designed to identify the relationship between capacity strain, disparities, and clinical outcomes for racial and ethnic minority patients. Determining the role of capacity strain and healthcare disparities for critically ill patients is crucial to (1) fully characterize the relationship between capacity strain, critical illness, and patient outcomes, (2) develop a framework for understanding how intrahospital operations may contribute to the development of disparities due to structural limitations, and (3) identify system-level targets for implementation initiatives designed to reduce healthcare disparities. Such analyses could be pivotal in reframing common understanding of disparities in critical illness by emphasizing the importance of intrahospital risk factors for their development. This would contrast to current interpretations that focus primarily on between-hospital factors that define high-performing and low-performing critical illness care centers. The goals of this study are to (1) understand the relationship between hospital-wide capacity strain, ICU triage, and racial/ethnic disparities in a population of patients with ARF and sepsis, and (2) assess for disparities between races/ethnicities in benefits due to ICU triage among patients with ARF and sepsis. First, I aim to use multivariable modeling techniques to identify important sociodemographic variables and assess for effect modification between various capacity strain metrics and patient race/ethnicity. Next, I aim to use causal effect methods to assess for ICU benefits among different patient race/ethnicities. This project will provide essential preliminary data for a planned NIH K-series Career Development Award that will (1) assess for the cumulative impact of capacity strain throughout a patients clinical care in the emergency department, ICU, and ward, (2) assess for economic dispariti...