Why are there so few women at the top of big US firms?

Although women moved into the work force in great numbers in the 1980s, they still have to catch up to men in terms of leadership positions in corporate America.

The New York human resources firm Catalyst found that women hold 16.9 percent of officer positions in US corporations, and only 11 percent of senior leadership line roles.

The question is, why are there so few women corporate board members? Those who have a proclivity to assume sex discrimination might fear the worst. Others might simply assume that relatively few qualified women were available for board slots, or that boards with women performed poorly in the marketplace.