PROJECT SUMMARY The emergency department (ED) has emerged as a critical context from which to address the U.S. opioid overdose crisis, which in 2021 alone accounted for over 80,000 deaths. This K02 Independent Scientist Award will enhance my research career with implementation science approaches to address multiple domains of the HHS Overdose Prevention Strategy from the emergency care setting. During this K02 award, I will augment my existing clinical expertise in emergency medicine and addiction medicine and current research portfolio spanning the continuum of opioid use and opioid use disorder with (1) new skills, knowledge, and training in implementation science, (2) advanced proficiency in clinical trial design, and (3) specialized professional development in team leadership and management. To accomplish these training objectives, I will leverage my ongoing R01-funded single site randomized trial evaluating an embedded ED physical therapy intervention as a non-opioid treatment modality for low back pain (R01HS027426, NCT04921449), which affects nearly 2 in 5 people and is the most common reason for acute and chronic opioid use. Specifically, I will (1) evaluate implementation outcomes across multiple partners engaged in my ongoing R01 trial, (2) gather qualitative data on contextual implementation determinants and preferred implementation strategies among current and future research partners for use in a future multi-site hybrid effectiveness-implementation trial, and (3) conduct a mixed-methods cost analysis of the embedded ED physical therapy care model to facilitate its scalability and long-term sustainability. This K02 award comes at an opportune time in my early- to mid-career transition, as it will provide me with a four-year period of intensive research focus to conduct these training and research activities, which I could not otherwise accomplish given my current clinical obligations as an emergency medicine physician. Following completion of this K02 award, I will apply the newly acquired implementation science expertise to accelerate and catalyze the translation of my research agenda to real-world practice, including primary prevention, harm reduction, and evidence-based interventions for opioid use disorder from the ED setting.