A report is presented on an analysis of sex factors in academic income variation as determined by achieved, ascribed, and university location characteristics. The study group consisted of 5450 individuals at a major midwestern university as of June 1971. The subjects included 4541 men and 908 women research assistants and associates, deans and vice presidents, editors, project directors, consultants, curators, and faculty. Findings demonstrate that achievements are the dominant income-determining variable for both sexes, but women's payment rates are lower and less subject to the variation of race, citizenship, and internal location; and that the ascribed and location characteristics also have sex-separate effects. It is concluded that while an achievement value governs reward, a universal sex standard does not. The achievement ideology operates, but it is practiced under sex separate standards and therefore academic income forms a dual reward structure. It is explained that sex work separation, and the normative structure of science, are among the mechanisms permitting and promoting the dual income structure. Extensive tables are included. (Author/PHR)