Noninvasive monitoring of liver fibrosis is an unmet and critical need within the clinical management of children with chronic liver disease. While liver biopsy is often used in the initial diagnostic evaluation of children with liver disease, subsequent surveillance liver biopsy is rarely performed in children because of its inherent invasiveness and risks. Therefore, our understanding of the natural history of fibrosis progression in children is limited. The patchy nature of fibrosis in many important pediatric liver diseases \[e.g. biliary atresia (BA) and cystic fibrosis liver disease (CFLD)\] limits the utility of sequential liver biopsy even if it were to be employed in clinical practice in pediatrics. Thus, non-invasive means of assessing liver fibrosis throughout the liver would be highly desirable and clinically useful in pediatric hepatology. ChiLDReN is poised and uniquely qualified to conduct a comprehensive longitudinal assessment of the utility of FibroScan™-specific elastography, liver stiffness measurement (LSM) as a measure of hepatic fibrosis in children with serious chronic cholestatic liver disease.