Patients with hypoplastic left heart syndrome and other single right ventricle lesions who have undergone the Fontan procedure have a high risk of neurodevelopmental disorders that affect quality of life and adulthood employment. This study will leverage the ongoing National Heart, Lung, and Blood Institute (NHLBI)-funded Single Ventricle Reconstruction Study by using innovative graph measures of brain connectivity to elucidate how alterations of the "connectome" in children with critical congenital heart disease are associated with developmental disabilities and their associated clinical risk factors. Improved understanding of these interrelationships may facilitate development of targeted interventions to improve outcome in the soaring population of adult Fontan survivors.