The present investigation was concerned with grading standards in different major fields. Specifically, adaptation-level theory was hypothesized as a model for describing grading behavior of instructors. In this model, the stringency of grading standards is positively related to average student ability. The regressions of GPA on HSGPA, SATV and SATM were computed for students in each of 12 major fields. This information was used to “project” hypothetical GPA’s if students were to major in fields other than their own. The results indicated that for middle and low ability students those fields with lowest ability students adopt lowest grading standards. Similarly, high grading standards are adopted by fields with high ability students. It appeared that adaptation-level theory was supported as a model of grading behavior at low and middle levels of ability but not for high levels of ability. The implications of the results were discussed with regard to: 1) changing college admission requirements, and, 2) open-enrollment experiments.