Douglas M. Branson, professor of business law at the University of Pittsburgh, is the author of a new book, Last Male Bastion – Gender and the CEO Suite at America’s Public Companies (Routledge). Women For Hire talked to him.

How did your expectations of how women have fared in management over the past 50 years compare to the reality?

Not very well. Women have been graduating from the law, MBA and graduate schools in great numbers since the 1970s (over 30% back then, over 40%, or more, today). Women constitute more than 50% of the workers and 50% of the middle managers in corporate America today. So the expectations have been high for quite some time.

Yet women are only 3% of the CEOs and a similarly small percentage of the senior managers. There were no women CEOs at the start of 1997 (Jill Barad was the first, at Mattel Toy). The number of female CEOs fell to 2 as recently as 2002. Today the number is 15, representing significant progress from none but paltry progress if we take the (even slightly) longer view.

If you had three reasons for why women face a glass ceiling, what would they be? Is it all tied to motherhood. Or not?

Linguists (Robin Lakoff, Deborah Tannen) point out that many women use inflections, modifiers, verbal hedges and other behaviors more than men do. Women speak in a different register. Many males ascribe to this behavior characteristics thought ill-suited for business (too emotional, intuitive, not analytical). Behavioral science proves that absolutely no connections exist. Yet men persist in this false belief and it holds women back.

Similarly, socialists (Rosabeth Moss Kantor is one) point out the negatives in other stereotypes assigned women (queen bee, ice queen, mother figure, mascot). Some women purposely seek out stereotypes themselves to limit their downside risk (iron maiden, class clown).

Stereotypes limit downside risk but also severely handicap upside potential. Stereotypes often accompany token (only woman) or skewed group (two women) status. Although it sounds simplistic, 3 seems to be the magic numbers (3 in a work group, 3 or more at a management level, 3 on a corporate board), liberating women or other minorities from token type status and stereotypes.

Motherhood, or the price of motherhood, is not the only reason women may face a glass ceiling but it certainly is a big one. Women still bear all the child birth and most of the child rearing duties in families, although males bear a greater load than they did in the 50s, 60s or 70s.

If women take any time off other than a minimum maternity leave, have additional children, or otherwise go on the mummy track, despite returning to work, at age 40 they will earn only 60% of what comparable males make. So the price of motherhood is not only too high – it is ridiculously high.

Anticipating the high cost, many qualified women opt out in their mid 30s, never returning to their chosen career path.

The situation is improving, as many companies realize that the difference between a male’s working life (e.g., 39 years) and that of a female employee who takes time to have 2 or 3 children (e.g., 37 years) is statistically insignificant.

Enlightened companies have instituted alumnae and welcome back programs which keep opt outs connected and facilitate their return to their employers when they feel it appropriate.

You look closely at 21 women who have beaten the odds and led Fortune 500 companies. In a nutshell, what do they all have in common?

All, save one, are plowhorses rather than showhorses. On the way up through the corporate ranks, all developed reputations as capable problem solvers. All had some (not exhaustive) grounding in economics and financial subjects (how markets work, financial markets, how to read financial statements, etc.).

I’m just starting out in the workplace, I’m smart, and I want to beat the odds. What should I not do?

Be overly aggressive and assertive (which the advice books counsel you to be). This is the 21st century. Those tactics don’t work anymore, if they ever did. Worse yet, they can sidetrack or derail a career.

Stand out too much. Australians term it the “tall poppy syndrome.” Stand out too much and you very well could get cut off at the base (or the knees).

Backstab and rumor monger. Tokens and skewed group members achieve the best results by sticking together and cooperating, not by competing against one another, cutthroat or not.

On the flip side, what are several things I should do?

Continue your education, if you can. Sixteen of the 21 women CEOs have advanced degrees (1 law, 14 MBAs. 1 MBA with a PhD). All 21 are university graduates. Education matters more for women than it does for men.

Look where they (other women) aren’t. The worst industries for hiring and promoting women are computer software and hardware. The obvious places, too – fashion, travel, publishing, perhaps retailing – do not treat women employees well.

Conversely, industries closed to women 30 years ago today offer careers and ample opportunities for advancement to women. Corporations in tobacco, electric and gas utilities, chemicals and paint, agribusiness, oil and gas, and insurance all have women CEOs.

Have children if you wish. Opt back in afterward. Of 21 women CEOs, 20 have children (the total is 20 women with 43 children). Several women CEOs have 3.

As women progress into the ranks of upper management, having children and a home life become much more important. “I need my children more than my children need me,” concludes Brenda Barnes, CEO of Sara Lee Corp.