Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the United States, affects 30% of adult Americans, may progress to nonalcoholic steatohepatitis (NASH) and end-stage liver disease, and is a risk factor for diabetes and cardiovascular disease. The diagnosis, grading, and staging of NAFLD currently is based on liver biopsy examination with histologic assessment. Noninvasive image-based methods to evaluate the liver in adults with NAFLD are urgently needed. We developed a quantitative ultrasound (QUS) method that in animal studies shows promise for detection and quantification of liver fat content. The current study's contribution is to extend the work to human participants by assessing the accuracy of backscatter coefficient and attenuation coefficient for detection of hepatic steatosis in a cohort of adult participants with NAFLD and non-NAFLD controls. QUS parameters measured using routine clinical US scanners show promise for detecting and perhaps grading NAFLD.