Overdose is a national top-three leading cause of pregnancy-associated death, and maternal substance use disorder (SUD) accounts for an estimated $1.5 billion in annual healthcare expenditures. Treatment with medication and behavioral therapy reduces morbidity and overdose risk. However, in published studies and in our data (n=186), 55% to 80% of patients discontinued treatment within one year postpartum. Additionally, as a result of systemic inequities, historically marginalized patients are at greatest risk of overdose or death. We urgently need interventions that can equitably improve treatment retention and SUD outcomes. One of the most effective SUD treatment strategies in non-pregnant populations is contingency management (CM), in which patients receive incentives to adhere to treatment. In pregnant populations, CM is efficacious for tobacco cessation. However, CM has only been tested in small and underpowered trials for other maternal SUDs, and the results have been mixed. Our central hypothesis is that CM will improve SUD treatment retention and reduce maternal morbidity and overdose risk in patients, moderating the impact of social determinants of health (SDoH) on outcomes. To test this hypothesis, we will design and conduct a hybrid efficacy-implementation randomized control trial within the Clinic for Acceptance, Recovery, and Empowerment (CARE) in Pregnancy at Washington University in St. Louis, which offers prenatal care, addiction treatment, and extended postpartum support for ~125 diverse patients per year facing the challenges of a SUD. In the R61 phase, in conjunction with our Community Advisory Board and the Center for Advancing Health Services, Policy & Economics Research, we will gather feedback from our partners (patients, providers, payers) to develop and pilot a standardized protocol to address social needs (Aim 1), and develop and pilot a protocol for delivering CM in CARE (Aim 2). In the R33 phase, we will recruit 270 patients who will undergo standardized documentation and management of social needs, and then be randomized to usual care or the CM program. We will assess the efficacy of CM to improve treatment retention and other SUD outcomes of pregnant patients with SUD for up to three years postpartum (Aim 3), use moderation modeling to define the relationships between SDoH services (exposure), CM (moderator), and treatment retention/maternal SUD outcomes (outcomes) (Aim 4), and assess implementation outcomes of reach, adoption, and implementation (Aim 5). If we prove CM efficacious to improve maternal SUD outcomes, our work will lead to a scalable, sustainable, effective interventions to maximize the health and wellbeing of patients and families affected by maternal SUD. This study is part of the NIH’s Helping to End Addiction Long-term (HEAL) initiative to speed scientific solutions to the national opioid public health crisis. The NIH HEAL Initiative bolsters research across NIH to improve treatment for opioid misuse...