Part of the problem is that wage data are largely kept secret in America, so women and minorities can be underpaid without knowing it. Employers frequently have policies that forbid workers from discussing their salaries, even though these policies are unfair and sometimes unlawful. Yet corporate cultures continue to intimidate workers by making it taboo to discuss salary, even among trusted co-workers.

In addition, because women often don't know what a job truly pays, she can undervalue herself when negotiating a new salary (and that can label her as an underachiever). So not knowing about wage discrepancies can perpetuate them.

Taking an employer to court under the Equal Pay Act, Title VII of the Civil Rights Act, or appropriate state laws is an option out of reach for many women. "I don't have $250 for an initial consultation with an attorney," said one woman who contacted NCPE. Because awards are severely limited in Equal Pay Act cases, there is a lack of incentive for attorneys to accept cases.

In addition, pursuing an equal pay case can wreak havoc on the personal lives and finances of the plaintiffs. Employers often fight back aggressively and ruin an employee's credibility as they seek to defend the company. Retaliation against women who file claims is common. NCPE has talked with plaintiffs who say their supervisors have turned hostile, their offices were moved to undesirable locations, that negative letters appeared in their personnel files, that their gynecological medical records were subpoenaed in an attempt to intimidate them, or that they were fired outright. This kind of treatment can last years while a case weaves its way through the legal process. Even if a woman wins her Equal Pay Act case, she may be labeled a troublemaker and have a hard time finding another job within the industry.

Given their lower earnings, women are usually the parent who takes time off to raise small children. That means they are out of the workforce for a few years, which lowers their earnings when they return.

But not all women are taking time off - many families rely on two paychecks and cannot afford for one parent to stay home. A 1992 study by the international executive search firm Korn/Ferry found that, of women in senior management positions in Fortune 1000 industrial and 500 service companies, only a third had taken a leave of absence, and most took fewer than six months off.

Shouldn't families be able to have pay equity and children?

Sometimes the jobs dominated by women in a company are not valued in the same way that men's jobs are. Studies have shown that the more women and people of color fill an occupation, the less it pays. Using a point factor job evaluation system, the state of Minnesota found that the "women's jobs" paid 20 percent less on average than male-dominated jobs, even when their jobs scored equally on the job evaluation system. (Pay equity adjustments were phased in over four years at a cost of 3.7 percent of overall payroll.)