Many states have "prudent layperson" mandates that require health plans to reimburse hospitals for emergency department (ED) care delivered to patients who believe that they have symptoms warranting emergency treatment. Increased, and possibly unnecessary, ED use has often been attributed to these policies. We use data from thirty-five states to study relationships between passage of prudent layperson policies in the late 1990s and ED use among the privately insured. None of the analyses show evidence that the mandates are associated with increased use. We conclude that prudent layperson mandates are not associated with increases in ED visits among privately insured patients.