PROJECT SUMMARY The landmark Healthy Brain and Child Development (HBCD) study will provide a representative reference data resource to the scientific community enabling unprecedented investigation of neurodevelopment and the impact of environmental, genetic, and biological factors on brain and behavioral health and developmental trajectories from infancy through childhood. Through this study, the Healthy Brain and Child Development National Consortium (HBCD-NC) will recruit and retain a sociodemographically diverse cohort of 7,500 pregnant women from 24 sites across the U.S. and follow these families and their children through the first decade of life. Children will undergo rigorous data collection across modalities including neuroimaging, neurophysiology, behavioral and cognitive assessments, and collection of biospecimens via a balanced protocol developed by field-leading experts. Building upon the substantive complementary experience and expertise of its multidisciplinary team and leveraging multiple population-specific technical innovations, the Healthy Brain and Child Development National Consortium Data Coordinating Center (HDCC) will provide the leadership, management, and oversight of data collection, quality control, curation, processing, management, sharing, and analytics to facilitate and support the activities of the HBCD-NC and ensure its success. Included is development and implementation of an optimized, state-of-the-art MRI protocol harmonized for the first time in infants/toddlers across all three major vendors which leverages the latest innovations in scanner technology with age-specific structural, microstructural, quantitative, functional, and spectroscopy sequences. Also detailed is a targeted EEG protocol linked with a field-leading automated processing pipeline for developmental EEG which provides innovative derivative measures. Data and project management will occur through a centralized tracking and distribution platform linked to a high-throughput compute backbone which overcomes limits of commercially-available systems for management and integrated processing of multimodality data from large, multi-site studies. High performance computing will be supported through unique access to a combination of field-leading resources. Detailed procedures are outlined for secure collection, management, and analysis of personally identifiable information (PII) data, including flexible methods designed to accommodate heterogeneity in electronic health record systems across sites. Finally, substantive HBCD-specific enhancements to the Data Exploration and Analysis Portal (DEAP 2.0) will produce a crucial tool for data access to authenticated users while promoting best practices in reproducible statistical analysis and providing flexible computation without the need to download restricted-access data. The result of this field- leading combination of HDCC resources will be a state-of-the-art, longitudinal data set of unparalleled scale which provides deep understanding of the biological and environmental factors that affect a child?s health, brain, and behavioral development and shapes research, clinical care, and public policy for decades to come.