There are differences among secondary schools along numerous dimensions such as characteristics of their entering students, their faculty, curricula, physical plants, and grading standards to name just a few. It seems quite reasonable to expect that as a result of some of these differences numerically equivalent grade-point averages or high school ranks in different schools will have quite different meanings in respect to predicting college success. Some sort of an adjustment of school grades would seem desirable if relevant inter-school differences are to be taken into account for purposes of prediction.