The COVID-19 pandemic puts individuals recovering from opioid use disorders (OUDs), an already vulnerable population, at increased risk of overdose due to decreased access to treatment, decreased social support, and increased psychosocial stress. This proposal will test the efficacy of a promising mobile app-based peer support program, compared to usual care, in increasing recovery capital, improving retention in treatment, and reducing psychosocial adverse effects, among a national sample of people in recovery from OUD. If effective, it would provide an accessible, personalized, and scalable approach to OUD recovery increasingly needed during the COVID-19 pandemic.