PROJECT SUMMARY Of the 250,000 annual patients in the United States with acute pulmonary embolism (PE), the majority are at low risk for morbidity and mortality. In fact, evidence-based guidelines suggest that up to 50% of patients with an acute PE are at sufficiently low risk for complications that they can be safely managed without hospital admission. Yet fewer than 5% of patients nation-wide are currently discharged for outpatient management. Reliable access to anticoagulant medications and outpatient follow-up are commonly cited barriers to outpatient management. However, prevailing heuristics used by Emergency Medicine clinicians to enable rapid decision-making also firmly link acute PE with hospital admission, and likely makes behavior change for these busy clinicians more challenging. Multiple prior efforts to reduce hospital admission for low-risk patients with acute PE have been limited by single-center designs, inclusion of homogenous and highly-resourced health systems, or have lacked a robust implementation plan underpinning to their design and evaluation. Using the diverse, state-wide Michigan Emergency Department Improvement Collaborative (MEDIC), we will refine, tailor, and evaluate a multi-component intervention suitable for broad dissemination to increase the use of outpatient management of low-risk acute PE for patients presenting to the emergency department. Following an implementation mapping approach built upon published literature and our preliminary findings, our intervention will address key barriers identified by a diverse group of stakeholders by combining traditional implementation science and behavioral economics strategies. Importantly, electronic alerts will be informed by user-centered design approaches to fit within the clinician workflow and decision-making process and “right sized” to appear only for applicable patients. Evaluation will include both quantitative and qualitative elements from the RE-AIM implementation evaluation framework. This multi-component intervention will facilitate a patient-centered approach to clinical decision-making that improves value by reducing unnecessary hospitalization for patients with low-risk PE. Furthermore, by tailoring and evaluating this intervention within a diverse set of hospitals, our multi-component intervention will be well positioned for dissemination nation-wide. Finally, our use of multi-site implementation mapping will provide a blueprint for other multi-site collaboratives interested in improving outcomes for a broad array of clinical conditions through rigorous quality improvement and implementation initiatives.