Mobile Mindfulness Training (mMT) for People in Medication Treatment of Opioid Use Disorder (MOUD)

Inclusion Criteria: * Clinically diagnosed with Opioid Use Disorder (per DSM5 criteria) * Currently enrolled in treatment for Opioid Use Disorder at a clinic affiliated with UKHealthCare or University of Kentucky * On a stable dose of buprenorphine, buprenorphine/naloxone, or naloxone (i.e., at least 30 days post-induction and on a stable dose for 30 days) * Able to read and understand English * Have a history of childhood trauma as measured by the Adverse Childhood Experiences scale and/or Childhood Trauma Questionnaire. Exclusion Criteria: * Currently taking a beta-blocker, calcium-channel blocker, antiarrhythmic, corticosteroid, or immune modulator medication * Uncontrolled acute or chronic health conditions (e.g., active infections, autoimmune conditions, cancer undergoing active treatment) * Current or expected pregnancy * Current mindfulness practice (i.e., participant reports practicing mindfulness for 10 minutes or more per week) * Primary psychotic illness * Diagnosis of a disorder known to interfere with neurocognitive function (e.g., estimated full scale IQ below 70 or diagnosis of dementia)