PROJECT SUMMARY The US is in the midst of an unprecedented pain management crisis. Low back pain (LBP) is the most common chronic pain condition in adults and the leading cause of disability worldwide. Guidelines have recommended non-pharmacologic treatments like spinal manipulation and behavioral approaches for LBP for nearly a decade, yet uptake and adherence has been poor. Moreover, little is known about the role of these treatments in the secondary prevention of chronic LBP (cLBP), especially for patients with biopsychosocial risk factors. With burgeoning costs, mounting evidence of ineffectiveness, and harms of commonly used drug treatments, including opioids, there is a critical need for research on non-pharmacological treatments for cLBP prevention that can be readily translated to practice. The long-term objective is to reduce overall LBP burden by testing scalable, first-line, non-pharmacologic strategies that address the biopsychosocial aspects of acute/sub-acute LBP and prevent transition to cLBP. We propose a novel randomized hybrid trial addressing both effectiveness and implementation. A total of 1180 patients will be enrolled with nonspecific LBP of 2-12 weeks duration, at medium or high risk of developing cLBP. This multi-site, predominantly pragmatic, phase III trial has two main aims. Aim 1 will assess the effectiveness of Spinal Manipulation Therapy (SMT), Structured Self-Management (SSM), and SMT+SSM relative to Usual Medical Care (UMC) in a randomized trial using a 2x2 factorial design. Physical therapists (PT) and chiropractors (DC) will deliver SMT and SSM, and primary care clinicians will deliver UMC. Primary outcomes are prevention of cLBP at 12 months; recovery from acute/sub-acute LBP at 6 months; and cumulative reduction of pain and disability over 1 year. Secondary outcomes include PROMIS-29, productivity loss, healthcare and medication use (including opioids). Aim 2 will use mixed methods to gather data about influences on the interventions that could affect interpretation of results and future implementation. Qualitative data will lend context regarding patients', providers', and health system leaders' perceptions of barriers and facilitators; quantitative data collection will offer insight into intervention application, adherence, fidelity, and provider confidence. Aligned with the National Center for Complementary and Integrative Health's (NCCIH) Strategic Plan 2016, this project can significantly transform LBP management by providing definitive and generalizable evidence regarding front-line, non-pharmacologic interventions addressing physical and psychosocial factors for the prevention of cLBP. Using PTs and DCs to empower patients to engage in healthy pain management behaviors, we anticipate LBP-related disability, productivity loss, and reliance on continued healthcare and medication use (including opioids) will be reduced.