Li Y, Thompson WK, Reuter C, et al. - In the nonclinical pediatric population, researchers evaluated the overall prevalence of incidental findings in brain magnetic resonance imaging (MRI) as well as the rates of specific findings and findings for which clinical referral is recommended. This cohort study was based on the April 2019 release of baseline data from 11,810 children, aged 9 to 10 years, who were recruited and completed baseline neuroimaging in the Adolescent Brain Cognitive Development (ABCD) study, the largest US population-based longitudinal observational study of brain development and child health. In total, 11,679 children (52.1% boys, mean [SD] age, 9.9 [0.62] years) had interpretable baseline structural MRI results. In the general pediatric population, both incidental findings in brain MRI and findings with potential clinical significance are common. Out of the total, 2,464 participants (21.1%) had IFs; around 4% of the scans showed incidental findings for which nonurgent or urgent clinical referral was recommended. The ABCD study has the potential to determine the significance of many common incidental findings by evaluating incidental findings and concurrent developmental and health measures and following these findings over the longitudinal study course.