This paper was presented at a symposium on "Recent Developments in Testing" on March 25, 1959, at the American Personnel and Guidance Association. A study is described, focusing on school administration, that represents an attempt to start at the other end to build a criterion measure. If successful, such a measure would be useful in supplying a criterion against which to evaluate selection tests. It would provide a better understanding of the domain of behavior to be predicted. Having such an understanding could contribute to the development of better predictors as well as to their validation.