This paper shows that a large fraction of the 1973–2003 growth in residual wage inequality is due to composition effects linked to the secular increase in experience and education, two factors associated with higher within-group wage dispersion. The level and growth in residual wage inequality are also overstated in the March Current Population Survey (CPS) because, unlike the May or Outgoing Rotation Group (ORG) CPS, it does not measure directly the hourly wages of workers paid by the hour. The magnitude and timing of the growth in residual wage inequality provide little evidence of a pervasive increase in the demand for skill due to skill-biased technological change.

The paper presents descriptive evidence from quantile regressions and more “structural” estimates from a human capital model with heterogenous returns to show that most of the increase in wage inequality between 1973 and 2005 is due to a dramatic increase in the return to post-secondary education. The model with heterogenous returns also helps explain why both the relative wages and the within-group dispersion among highlyeducated workers have increased in tandem over time. These findings add to the growing evidence that, far from being ubiquitous, changes in wage inequality are increasingly concentrated in the very top end of the wage distribution.