Both marital status and computer usage on the job have been found to increase earnings by as much as two
additional years of schooling. If correct, these findings suggest that factors other than long-term human
capital investments are key determinants of earnings. Data on identical twins are used in this paper to sweep
out selection effects and examine the effect of marital status and computer usage on wages. Within-twin
estimates indicate that, unlike education, job tenure and union status, neither marital status nor computer
usage have a large or significant effect on wages.