Since 1950, U.S. educational attainment has increased substantially. While
the median student in 1950 dropped out of high school, the median student
today attends some college. In an environment with ability heterogeneity and
positive sorting between ability and school tenure, the expansion of
education implies a decrease in the average ability of students conditional
on school attainment. Using a calibrated model of school choice under
ability heterogeneity, we investigate the quantitative impact of rising
attainment on ability and measured wages. Our findings suggest that the
decline in average ability depressed wages conditional on schooling by 31-58
percentage points. We also find that the entire rise in the college wage
premium since 1950 can be attributed to the rising mean ability of college
graduates relative to high school graduates