ABSTRACT: PROJECT 1 CEREMONY Pregnant and postpartum American Indian and Alaska Native people (Native mothers) face a more than two- fold higher risk of maternal mortality compared to non-Hispanic White mothers. Deaths related to substance use (SU) and mental health conditions reflect a leading cause of preventable maternal mortality, including among Native mothers, making these conditions a strong target for reducing maternal mortality and morbidity. The Utah Maternal Mortality Review Committee (MMRC) has identified access to substance use disorder (SUD) treatment including medication for opioid use disorder (MOUD), mental health care, improved social support, decreased stigma against SUD, and care coordination, particularly in the postpartum period (when the majority of deaths occur) as actionable intervention points. The objective of our study, Culturally- Engaged REcovery – MOms connected through Native CommunitY (CEREMONY), is to adapt evidence-based perinatal care models that integrate pregnancy and postpartum care with SU/SUD treatment and care to meet the needs of Native mothers. With our partners at Sacred Circle Clinic, a federal Tribal Contract clinic operated by the Confederated Tribes of the Goshute Reservation, we are uniquely poised to respond to the expressed needs of Native mothers and stakeholders, who identified a lack of culturally-integrated SUD care as a significant gap in perinatal care for Native mothers. We will do this by building upon the strong, evidence- based foundation of our University of Utah integrated perinatal SUD clinic called Substance Use and Pregnancy – Recovery, Addiction, and Dependence (SUPeRAD). The SUPeRAD model directly addresses the actionable intervention points identified by the MMRC to prevent SUD-related maternal deaths, but is not specifically adapted to Native mothers’ needs. The rationale for this study is that there is a critical knowledge gap in the adaptation and implementation of integrated perinatal SUD care specifically for Native mothers. The CEREMONY study will fill this gap by adapting the SUPeRAD clinic model to the needs of Native mothers using the validated ADAPT-ITT adaptation framework, informed by human centered design and community-based participatory research (Aim 1); and then testing the adapted, culturally-integrated perinatal SUD care intervention at Sacred Circle Clinic using a Hybrid Type 1 effectiveness-implementation study (Aim 2a&b). The Hybrid Type 1 design will provide important, reliable data on the clinical effectiveness of culturally adapted perinatal SUD care for Native mothers (Aim 2a) while also producing novel data on the implementation process (Aim 2b). Successful completion of these Aims will provide implementation and training protocols that can be used to guide adaptation and implementation of culturally-adapted perinatal SUD care in other settings across the US. Our study is innovative and significant because it employs strong community engagement princip...