This paper examines the hypothesis that the gender salary gap observed in the academic labour
\nmarket is predominantly explained by the differing average characteristics of male and female
\nacademics and barriers to female promotion. Preliminary analysis reveals that the crowding of
\nwomen into the lower rungs of academia is a strong determinant of their lower average salary.
\nThis effect should be transitory as young women, now entering the profession, move up its
\nranks. We construct a rank attainment model and investigate the current and predicted
\ndistribution of females across ranks. Significant evidence of barriers to female promotion is
\nrevealed.