This paper attempts to unravel supply and demand factors of work-relat
ed training by exploiting information from workers who wanted to recei
ve such training but did not get it. Workers' willingness to receive t
raining varies with their level of education, background characteristi
cs, and job characteristics, Firms' gains from training vary across in
dustries, and with workers' gender and age. Half of the untrained work
ers are not trained because the net returns to the worker would be neg
ative, while the net returns to the firm would be positive. For anothe
r third of the untrained workers exactly the opposite is the case.