This paper yields new insights into why similar workers are paid differently by surveying a representative sample of Danish firms and linking responses to administrative data. We find that a substantial minority of firms, about 18 percent, have inaccurate beliefs about their position in the wage distribution. Inaccurate beliefs are more likely to occur in smaller firms. To study the implications of firms’ inaccurate beliefs, we build a simple model with monopsonistic firms. Using our survey, we elicit firms’ motives for setting high wages. The dominant motive aligns with wage-posting models, i.e., retaining and attracting new employees. The least common motive is compensating for negative job characteristics.