We examine an employer's preferences regarding the education, prior ex
perience, or training of the worker she hires. Although a worker's edu
cation may be observable, his productivity on the job is often private
ly observed. Higher levels of education increase the chances that the
worker will have high productivity on the job. The employer's preferen
ces are shown to depend critically on the nature of the adverse select
ion problem she faces: high levels of education are favored for worker
s with idiosyncratic skills, while low levels of education are preferr
ed for versatile workers, whose skills are transferable.