Online Yoga vs Acceptance and Commitment Therapy for Treating Chronic Musculoskeletal Pain

Inclusion Criteria: * Veteran of the United States Armed Forces ≥ 18 years old * Chronic pain \> 6 months related to at least one musculoskeletal pain-related diagnosis indicated by an ICD-9 or -10 code * Minimum pain intensity at screening ≥4 on a 0-10 using the Defense and Veterans Pain Rating Scale (DVPRS) * Not begun new pain treatments or medications in the past month * Stable medication regimen for at least 4 weeks prior to entry to the study * English literacy * Internet connection at home Exclusion Criteria: * Participation in another clinical trial, unless given prior authorization from both our research team and that of the other study * Back surgery within the last 12 months * Back pain potentially attributed to a specific known condition * Baseline pain \<4 or ≥9 on a 0-10 Numeric Rating Scale * Unstable, serious coexisting medical illness, mental illness or psychiatric conditions * Attended or practiced yoga ≥ 1 x in the past 12 months * Current suicidal intent or plan * Has received ACT in the past