It might seem natural to gauge the amount of discrimination in labor markets by looking at the average wages of different groups. For instance, in recent years the wage of the average black worker in the U.S. has been about 20 percent less than the wage of the average white workers. The wage of the average female worker has been about 30 percent less than the wage of the average male worker. These wage differentials are sometimes presented in political debate as evidence that many employers discriminate against blacks and women. Yet there is an obvious problem with this approach. Even in a labor market free of discrimination, different people have different wages. People differ ill the amount of human capital they have and in the kinds of work they are able and walling to do. The wage differences we observe in the economy are, to a large extent, attributable to the determinants of equilibrium wages. Simply observing differences in wages among broad groups say little about the prevalence of discrimination. Consider, for example, the role of human capital. About 80 percent of white male workers have a high school diploma, and 25 percent have a college degree By contrast, only 67 percent of black male workers have a high school diploma, and only 12 percent have a college degree. Thus, at least some of the difference between the wages of whites and the wages of blacks can be traced to differences in educational attainment, Similarly, among white workers, 25 percent of men have a college degree, whereas only 19 percent of women have a college degree, indicating that some of the difference between the wages of men and women is attributable to educational attainment. In fact, human capital is probably even more important in explaining wage differentials than the foregoing numbers suggest. For many years, public schools in predominantly black areas have been of lower quality than public schools in predominantly white areas. Similarly, for many years, schools directed girls away from science and math courses, even though these subjects may have greater value in the marketplace than some of the alternatives. If we could measure the quality as well as the quality of education, the differences in human capital among these groups would seem even larger. Human capital acquired in the form. of job experience can also help explain wage differences. In particular, women tend to have less job experience on average than men. One reason is that female labor-force participation has increased over the past seven decades. Because of this historic change, the average female worker today is younger than the average male worker. In addition, women are more likely to interrupt their careers to raise children. For both reasons, the experience of the average female worker is less than the experience of the average male worker. Yet another source of wage differences is compensating differentials. Some analysts have suggested that women take more pleasant jobs on average than men and this fact explains some of the earnings differential between men and women. For example, women are more likely to be secretaries, and men are more likely to be truck drivers. The relative wages of secretaries and truck drivers depend in part on the working conditions of each job. Because these nonmonetary aspects are hard to measure, it is difficult to gauge the practical importance of compensating differentials in explaining the wage difference that we observe. In the end, the study of wage differences among groups does not establish any clear conclusion about the prevalence of discrimination in U.S. labor markets. Most economists believe that some of the observed wage differentials are attributable to discrimination, but there is no consensus about how much. The only conclusion about which economists are in consensus is a negative one: Because the differences in average wages among groups in part reflect differences in human capita