The article studies the U.S. earning trends since 1950 and gives explanations for the inequality in earnings. Both slow growth and increased inequality appear in the comparison of adult male earnings distributions for 1979 and 1987. Trends in women's earnings paint a somewhat brighter picture. Women, like men, have experienced slow hourly wage growth and growing wage inequality. But in terms of annual earnings, both factors have been offset by changes in hours worked. The result is a significant increase in the proportion of women who earn $20,000 a year or more. A combination of shifts in supply and shifts in demand is necessary to explain the observed trends between these groups. A critical aspect of supply shifts was the entry into the labor market of the well-educated baby boom generation. Demand shifts can be characterized as a long-term trend toward increasing relative demand for highly skilled workers. The growth in within group earnings inequality has many potential explanations, but it is not well understood and contains opportunities for future research.

Using data from two longitudinal surveys of American high school seniors, we show that basic cognitive skills had a larger impact on wages for 24-year-old men and women in 1986 than in 1978. For women, the increase in the return to cognitive skills between 1978 and 1986 accounts for all of the increase in the wage premium associated with post-secondary education. We also show that high school seniors' mastery of basic cognitive skills had a much smaller impact on wages two years after graduation than on wages six years after graduation.