This article reports a study of aggregate unit salary levels, within a major research
university. We analyze these salary levels, as they are influenced by unit sex composition,
and modified by unit attainment levels—where unit refers to the departments, colleges and
schools, and other academic divisions of the university. We investigate three central issues
of sex and salary, previously overlooked in salary studies of academic employees: Do high
proportions of women depress men's unit salary levels ("competition" hypothesis)? Are
women's salary levels higher in male-dominated, and lower in female-dominated, units
("concentration" hypothesis)? Are men salary-compensated for working with women
("compensation" hypothesis)? The findings support none of these hypotheses. Rather, the
relationship between unit sex composition and salary rests upon the connection between
units' composition and attainment levels.