RecruitingBehavioural interventionPeer Recovery to Improve Polysubstance Use and Mobile Telemedicine RetentionThe purpose of this study is to evaluate the feasibility and effectiveness of a peer-led, brief, behavioral intervention to improve adherence to medication for opioid use disorder (MOUD) and reduce polysubstance use among patients with OUD and polysubstance use in underserved areas. The intervention is based on behavioral activation (BA) and is specifically designed to be implemented by a trained peer recovery specialist. In this hybrid, Type-1 effectiveness-implementation randomized controlled trial (RCT), the investigators will evaluate the effectiveness and implementation of Peer Activate vs. treatment as usual (TAU) over twelve months.