PROJECT SUMMARY/ABSTRACT Brain development occurs at a rapid pace prenatally and throughout childhood, impacted by dynamic genetic and environmental influences. Studies using advanced neuroimaging have provided significant insights into brain development but have been limited by small sample size, especially for high-risk populations. Substance- exposed infants are at particularly high risk for adverse outcomes; however, findings are inconsistent, making it difficult to disentangle prenatal exposure effects from other adverse influences. The objectives of our HEALthy Brain and Child Development (HBCD) Prenatal Experiences and Longitudinal Development (PRELUDE) consortium are to characterize typical trajectories of brain development from birth through childhood, measuring the influence of key biologic and environmental factors and their interactions on child social, cognitive, and emotional development. We will assess how children prenatally exposed to opioids and other substances, as well as environmental adversity, differ in those brain trajectories and outcomes. Our consortium consists of six centers (Arkansas Children?s Research Institute, Case Western Reserve University, Cincinnati Children?s Hospital, Children?s National Medical Center, University of North Carolina at Chapel Hill, and Vanderbilt University) which have collaborated previously and have complementary expertise in neuroimaging, neurophysiology, longitudinal clinical research, child development, substance exposure and addiction, ethical/legal issues, and clinical care of high-risk infants/children. The PRELUDE consortium will recruit 680 pregnant women with substance use, 680 at-risk pregnant women without substance use, and 1360 comparison pregnant women representative of the general population to contribute to the overall HBCD study. We will work closely with the other sites, the HBCD Consortium Administrative Core, and the HBCD Data Coordinating Center to develop a comprehensive study protocol and ensure compliance of study workflow and data transfer. Our consortium has an optimized research protocol and 4 specific aims: 1) Employ ethical and evidence-based best practices to enroll and retain a diverse cohort of pregnant women into a longitudinal study of infant/child brain development, oversampling mothers from high-risk backgrounds and those using substances during pregnancy; 2) Engage a comprehensive array of maternal- and child-oriented community stakeholders to identify community concerns and priorities regarding this research, minimize risks, and promote long-term engagement of the recruited child-mother dyads; 3) Collect rich data to examine how maternal health context and broader environmental factors may affect the maternal-fetal dyad and neurodevelopment of children; 4) Capture key developmental windows during which maternal and environmental factors may interact with brain and behavioral development of children. The insights from these data will provide greater understanding of factors affecting early childhood brain development, allowing targeted interventions and improved outcomes for mother-child dyads.