The US is currently experiencing an opioid epidemic with opioid overdose, opioid use disorder (OUD) and Emergency Department (ED) visits related to opioids on the rise. The ED is at the forefront of this public health emergency and often a place where patients with OUD come for treatment of medical problems, both related and unrelated to opioid use. Medications for OUD (MOUD) and linkage to care from the ED are a critical piece in addressing this crisis. Patients in the ED with OUD present with a complex constellation of substance use, psychiatric and medical comorbidity, and often experience fragmented healthcare delivery. Comprehensive disease management strategies, such as the Collaborative Care model, hold great promise for addressing the treatment needs of patients with OUD in the ED. The Emergency Department Longitudinal Integrated Care (ED-LINC) intervention derives from the Collaborative Care model and is a multi-component, longitudinal intervention for patients with OUD and related comorbidity that is initiated during an ED visit. The ED-LINC clinical trial will randomize 500 patients with OUD seeking care at two Washington State EDs to the ED-LINC intervention (n=250) or usual care control (n=250) conditions. Patients randomized to the ED-LINC intervention will receive; 1) overdose education; 2) brief bedside intervention targeting motivation to engage in outpatient care; 3) a patient-centered approach to MOUD using a treatment decision support tool; 4) longitudinal and proactive care management which will proceed for three months along with weekly caseload supervision of the interventionist by a mental health professional allowing for stepped-up care targeting opioid use and associated comorbidity. ED-LINC is supported by the Emergency Department Information Exchange (EDIE) platform, which is a novel care coordination tool that collects data from hospitals in over 30 states and packages this information for emergency providers in real-time alert notifications. Further features of EDIE include creation of tailored care plans. The trial incorporates pragmatic outcome assessment elements, including the use of EDIE and statewide administrative data to assess important outcomes on the intent-to- treat sample. The ED-LINC trial tests the hypotheses that over time, patients randomized to the ED-LINC intervention, when compared to patients randomized to usual care, will demonstrate: 1) significant reductions in self-report illicit opioid use; 2) significant increases in MOUD initiation and retention, and 3) significant reductions in ED utilization. Secondary analyses will explore the impact of methamphetamine use comorbidity and sex on intervention treatment effects. The study team also plans to conduct an implementation process assessment using novel mixed methods to understand the potential for sustainable implementation of intervention elements. Data derived from this formative evaluation will be used to prepare for the presentation of stud...