Optimization and Multi-Site Feasibility of Yoga for Chronic Pain in People in YOGAMAT-II - Phase I

Inclusion Criteria: * Enrolled in methadone maintenance (MMT) or buprenorphine/naloxone (BUP) treatment for \> 3 months * Plan to continue treatment for next 6 months * Chronic pain, defined as pain for at least half the days over the previous three months, a mean score of 4 or higher on the Brief Pain Interference Scale (BPI; with reference to chronic pain), and pain severity of 4 or higher on a Visual Analog Scale (0-10) indicating "worst pain in the last week." Pain severity score will also refer to the areas of their body in which they have chronic pain. * Aged \> 18 * Proficiency in English sufficient to engage in informed consent in English, understand classes taught in English, and read short sentences * Available at least one of the times study classes are offered. Exclusion Criteria: * Currently taking yoga classes or practicing yoga at home once per week or more often. * Medical conditions that would make participation in yoga unsafe or not possible, including active malignancy treatment, fracture, recent joint surgery, use of assistive ambulatory devices other than a cane. . (In cases where this is unclear, site PI will make final determination based on available evidence.) * Severe or progressive neurologic deficits. (In cases where this is unclear, site PI will make final determination based on available evidence.) * Other severe disabling chronic medical and/or psychiatric comorbidities deemed by the site PI on a case-by-case basis to prevent safe or adequate participation in the study (e.g., cognitive impairment that prevents a participant from understanding assessments; history of disruptive behavior in medical settings; severe disabling heart failure or lung disease) * Surgery requiring overnight hospitalization planned in the next 3 months * Pregnancy * Plan to move out of the area within 6 months. * Homeless, defined as any time in the past month sleeping in a shelter or on the street.