Compared to a civilian population, Veterans have particularly high rates of severe chronic pain and Opioid Use Disorder (OUD). Prevalence of chronic pain in individuals with OUD remains high despite engagement in opioid agonist treatment (OAT), the first line treatment for OUD, consisting of buprenorphine or methadone. Chronic pain treatment in the Veterans Health Administration (VHA) has recently shifted to promoting non-pharmacologic approaches to treat chronic pain; however, individuals with OUD are often excluded from pain treatment clinical trials. Among individuals with chronic pain and OUD receiving OAT, the most commonly reported pain coping strategies are prayer, over the counter medication, and opioid medication. There is an immediate need to develop evidence-based pain treatments for chronic pain that can be integrated into OAT for Veterans with chronic pain and OUD. The gold standard non-pharmacologic treatment for chronic pain is cognitive behavioral therapy (CBT) for chronic pain. Despite having a favorable view of non-pharmacologic pain treatment, many OAT clinics lack adequate staffing training and resources for intensive pain treatment such as CBT. Furthermore, Veterans are often hesitant to seek care in pain specialty clinics due to stigma (e.g., drug-seeking behavior) and frequent OAT dosing visits. Walking is a core component of CBT for chronic pain and has demonstrated effectiveness at reducing pain in chronic pain patients. More specifically, walking has been identified as a low-cost, highly accessible intervention that has been shown to reduce pain, disability, and increase quality of life in individuals with chronic pain but has not been tested in Veterans with OUD engaged in OAT. The proposed study will determine feasibility, acceptability, and preliminary efficacy for Steps to Change (S2C), a behavioral pain treatment that includes biopsychosocial pain education and an adaptive walking program. Importantly, S2C will be offered within in the Veteran’s OAT clinic to increase access and encourage treatment engagement. Pain interference (primary outcome) collected using ecological momentary assessment (EMA), where behavior is repeatedly sampled using a mobile device. The use of EMA to measure pain interference offers considerable benefits to in-clinic measurement including significantly reducing recall bias and substantially improving reliability of measurement. Daily steps will be measured using a study provided pedometer and entered in end of day EMA surveys. Sixty Veterans will be randomized to either 1) S2C or 2) health education control each consisting of 4x60 minute weekly groups in the OAT clinic. All participants will complete EMA surveys for 8 weeks (1-week baseline, 4-week treatment, and 1-week post, 3- and 6-month follow up). We predict that study procedures will be feasible with timely randomization, comparable retention and EMA survey completion between treatment groups. We also predict that Veterans in both gr...