Women have comprised over half of US university students since the 1980s. Women make up 45% of the US workforce. However women are poorly represented in senior and leadership positions both in industry and on university faculties. Only 16% of corporate officers and only 2% of CEOs at major companies are women. If increasing numbers of women have been in the pipeline for over 25 years should more have emerged at the other end as leaders? A simple model indicates that the pipeline delay hypothesis is not sufficient to explain the relatively small numbers of women in senior and leadership roles.