Traditionally, patients with opioid use disorder (OUD) seen in EDs have been medically cleared, discharged, and left to navigate a complex treatment system after discharge. Replacing this system of care requires reimagining the ED visit to promote best practices, including starting treatment with lifesaving medications for OUD in the ED. In this article, the authors present stakeholder-informed design of strategies for implementation of evidence-based ED OUD care at Penn Medicine. They used a participatory design approach to incorporate insights from diverse clinician groups in an iterative fashion to develop new processes of care that identified patients early to initiate OUD care pathways. Their design process led to the development of a nurse-driven protocol with OUD screening in ED triage coupled with automated prompts to both nurses and physicians or advanced practice providers to perform assessment and treatment of OUD and to deliver evidence-based treatment interventions.