This review focuses on the diagnosis, risk factors, prevalence, pathogenesis and treatment of pediatric nonalcoholic steatohepatitis (NASH). NASH is a progressive form of nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease in children. The factors that account for differences between children with NASH and children with milder forms of NAFLD are unclear. The diagnosis of NASH requires interpretation of liver histology because no noninvasive markers predict the presence or severity of NASH. There is no proven treatment for NASH. Several clinical trials for NAFLD are in progress; however, clinical trials focusing on NASH are needed. Heightened physician awareness of NAFLD, NASH, and associated risk factors is important to identify and treat affected children.