Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease. Most cases are diagnosed incidentally in the primary care or hospital setting on the basis of elevated liver enzyme levels or hepatic steatosis on imaging. NAFLD encompasses a wide spectrum: The vast majority of patients have nonprogressive nonalcoholic fatty liver, and a few of those develop progressive liver injury, inflammation, and fibrosis, a condition termed nonalcoholic steatohepatitis. Cardiovascular disease is the leading cause of death in patients with nonalcoholic fatty liver disease. Persons with nonalcoholic steatohepatitis have increased liver-related mortality. In the absence of regulatory agency-approved drugs, lifestyle modification and weight loss remain the cornerstones of NAFLD therapy.