Chronic pediatric liver disease is a devastating group of conditions that have a profound effect on children, their families, and our society. Biliary atresia and the other cholestatic liver diseases studied by the Childhood Liver Disease Research Network (ChiLDReN) account for approximately half of liver transplants performed in children in the United States. A better understanding of the diseases studied by this network will help provide better care of patients with chronic liver disease. The gaps in our current knowledge regarding these diseases provide compelling scientific justification for the continuation of this multi-center network. The primary goal of this proposal is to continue longitudinal cohort studies and collect biosamples for potential ancillary studies in rare pediatric liver diseases that include: biliary atresia; Alagille syndrome; alpha-1-antitrypsin deficiency; progressive familial intrahepatic cholestasis syndromes; bile acid synthesis defects; mitochondrial hepatopathies; idiopathic neonatal hepatitis; and primary sclerosing cholangitis. The SDCC for the ChiLDReN study is charged with providing coordination, communications and logistical support, clinical study design, centralized data management, biosample management, quality assurance, and analytical support to the research sites and the NIDDK Project Scientist for all ChiLDReN studies.