The BCP aims to characterise brain and behavioural development in typically developing infants across the first five years of life in the United States of America. The BCP leverages two existing National Institutes of Mental Health (NIMH)-funded studies to supplement a hybrid accelerated longitudinal and cross-sectional study design. A total sample of 500 typically developing infants, toddlers, and preschool-aged children were recruited and enrolled between birth and 5 years of age. Participants were recruited from existing registries at the University of North Carolina (UNC) and the University of Minnesota (UMN) based on state-wide birth records and broader community resources. New mothers were approached at UMN and the UNC Hospitals Newborn Nursery.