Project Abstract The Parent Grant (R01 AT10742; PIs Price & Merrill) is a two-group randomized controlled trial, with repeated measures, designed to enroll a sample of 330 in medication treatment for opioid use disorder (MOUD) to assess the effectiveness of Mindful Awareness in Body-oriented Therapy (MABT) as an adjunct to medication treatment for opioid use disorder (MOUD). The national opioid epidemic requires development of real-world evidence-based treatments for opioid use disorder, including adjuncts to MOUD. Interventions are needed that address the complex needs of patients with opioid use disorder, which include substantial mental health co- morbidity (e.g. PTSD, depression) and high rates of chronic pain. MABT, a novel mindfulness-based intervention, uniquely addresses aspects of awareness, interoception, and regulation that may be associated with pain, mental health distress, and behavioral control that increase risk of relapse and poor treatment outcomes. The proposed Diversity Supplement examines two critical additional research questions. The aims are: 1) to describe the types of lifetime exposure to trauma and compare types of trauma exposure between men and women engaged in MOUD, and to examine the relationship between types of trauma exposure and symptomatic distress in this sample at baseline; and 2) to explore the underlying mechanisms of MABT by examining interoceptive awareness as a possible mediator of emotion regulation difficulties and other indicators of mental health distress. It is hypothesized that emotion regulation difficulties in MABT + TAU compared to TAU only will be mediated by increased interoceptive awareness from baseline to 3-month follow- up. This application thus addresses key gaps in knowledge that are important for consideration in MOUD treatment that may be critical for reducing relapse and improving treatment outcomes.