Nonalcoholic fatty liver disease (NAFLD) is a spectrum of disorders that encompasses simple hepatic steatosis and the more serious nonalcoholic steatohepatitis (NASH) that can progress to cirrhosis. Although the prevalence of NAFLD in childhood is not clear, it is apparently more common than originally thought. The major association with NAFLD is obesity, and as the prevalence of obesity in childhood and adolescence increases, fatty liver is recognized with greater frequency. Although the factors associated with progression of liver disease have not been determined fully, the pathogenesis of NASH is a "two hit" process that includes disturbed lipid homeostasis, resistance to the effects of insulin and subsequent hyperinsulinemia, and local toxic effects of triglyceride on hepatocytes. Treatment options are currently limited.