Opioid Use Disorder (OUD) is a national health crisis. Office-Based Opioid Treatment (OBOT) with buprenorphine/naloxone (B/N) prevents overdose deaths. Psychosocial stress and psychiatric problems (e.g., Anxiety) are major reasons for OBOT drop out and relapse. Many patients turn to benzodiazepines (BZD) to address anxiety and emotional distress with dangerous consequences. Nonpharmacologic approaches to anxiety, stress, and emotion dysregulation are needed during primary care OBOT, which is the primary access point for OUD treatment in most US counties. Mindfulness-Based Interventions (MBI) safely and reliably reduce the impact of stress, anxiety, depression, and chronic pain, which could increase OBOT retention, while reducing rates of relapse and overdose deaths. However, current 8-week standard MBIs do not appear to have strong, sustained impact on substance use outcomes, suggesting longer or enhanced MBIs are needed in the OUD treatment setting. This project originally proposed to adapt, refine, and compare the effectiveness of the 6-month live-online Mindful Recovery OUD Care Continuum (M-ROCC) versus a standard recovery group in primary care. M-ROCC is derived from the evidence-based, established Mindfulness Training for Primary Care (MTPC) program, which has been adapted for Opioid Use Disorder. M-ROCC includes a flexible, patient-centered, motivationally responsive design, including a Low Dose Mindfulness Entry Group, Mindfulness Maintenance Check-in Support Group, and an intensive Mindfulness Training for Primary Care (MTPC-OUD) Group. M-ROCC builds on the previously demonstrated ascending mindfulness practice dose ladder approach, which helps individuals with OUD nurture motivation and resolve ambivalence for mindfulness practice. MTPC has been shown to lower anxiety, stress, and depression, while increasing self-efficacy and capacity for behavioral change by engaging self-regulation mechanisms. During the R21 phase, we established the feasibility and acceptability of the M-ROCC program and prepared for the R33 phase by training providers and obtaining necessary approvals and site contracts. In the R33 phase, we planned to conduct a five-site RCT comparing M-ROCC versus Group-Based Opioid Treatment (GBOT). Due to the COVID-19 pandemic, we modified all aspects of the R33 phase to be conducted with a national sample in a remote, live-online, virtual format, comparing M-ROCC versus a standard online recovery group for 196 patients prescribed B/N for OUD, primarily evaluating its impact on opioid use and anxiety. We all evaluate effects on cocaine and BZD use, as well as aspects of self-regulation needed for sustained addiction recovery. Participants in the online clinical trial are recruited from multiple U.S. states through provider outreach and social media advertising.