Project Summary The opioid epidemic has resulted in widespread, detrimental public health consequences and disproportionally impacts vulnerable, high-risk groups including pregnant and postpartum women (PPW) and their babies. PPW with OUD also face high levels of self-stigma – the internalization of negative feelings about oneself because of drug misuse. Self-stigma is highly correlated with numerous detrimental consequences including recovery outcomes and reduced engagement with substance use treatment. Furthermore, self-stigma prevents treatment initiation and engagement among PPW with OUD, leading to additional adverse health outcomes for both mother and baby. Digital interventions have the potential to support healthier behaviors among PPW with OUD and may also provide a promising method for reducing their self-stigma. Enhearten is a digital intervention that is designed to foster adherence to medication for OUD and treatment retention while considering the unique needs of PPW, but it currently lacks features to decrease self-stigma. In this proposal, we will augment Enhearten with a stigma-focused ecological momentary intervention (EMI) designed to: 1) screen for feelings of stigma and 2) counteract these vulnerabilities via just-in-time interventions. Specifically, in Phase I, we will adapt Enhearten to include a new EMI feature and refine this tool using the Discover, Design/Build, and Test (DDBT) Framework to ensure that it will reduce self-stigma among this vulnerable population during critical moments. At the start of Phase II we will conduct an additional DDBT cycle to further increase the usability and efficacy of our EMI. Then, we will conduct an individual-level multicenter randomized controlled trial to test the feasibility, acceptability, and efficacy of Enhearten on reducing self- stigma and improving treatment adherence. Recruitment will occur from various clinics throughout the Midwest that specialize in treating PPW with OUD. Enhearten will be an invaluable tool for PPW with OUD by supplementing traditional in-person care, reducing self-stigma, and supporting continued motivation and adherence to their treatment plan during their recovery journey.