Women are poised to outnumber men in the workplace—so what’s it going to take for women to hold more of the country’s top jobs?

I believe most people in the country are equally comfortable hiring a female lawyer, meeting with a female financial adviser, and being interviewed by a female journalist—most, not all. Why is it, then, that women occupy only about 20 percent of leadership positions in business, journalism, politics and law. And the rate is much lower in Fortune 500 companies. Women who reach the highest ranks in business and other industries are still the exception. Most executives agree a glass ceiling keeps women from getting ahead. This class ceiling is the result of attitudes and biases in the workplace and society. Indeed, women tend to be held back not so much by blatant sexism as by outdated stereotypes about women’s abilities and their commitment to their career, says Sheila Wellington, former president of Catalyst, the nonprofit organization working to advance women in business. "Male stereotyping and preconceptions of women" are among the biggest barriers women still face, she says. Societal expectations continue to weigh on women, whether it’s limiting expectations of how women should behave and what they can do, or women’s own lack of confidence about whether they can get what they want in life. Here, a reminder of five of the approaches that are working:

Feed the Pipeline. If companies fill their pipelines with qualified, talented women, these women will break through to the higher ranks. Forward thinking companies work with their CEO and the board of directors to ensure that women are included in succession plans. At Abbott, the IL–based pharmaceutical company, the talent pipeline is reviewed each year to identify women who have the potential and the track record to compete for senior spots. Women can’t rise to the top if they’re not even in the running for the jobs.

Provide Mentors Having a mentor can be key to getting on the fast track to the top. Cultivating influential senior colleagues who believe in you and are impressed by your work can make all the difference: these mentors can champion your efforts and spread the word about your potential. Some companies, like Allstate, have a formal program in place. Their Women's Leadership Forum helps female employees get ahead with mentoring and leadership development. And at Ernst & Young, almost half of multicultural employees have participated in mentoring, including involvement in such programs as Women’s ACCESS, which pairs senior managers with partners.

Promote ERGs Employee Resource Groups are growing in popularity as ways for employees who are connected by a common factor, such as gender, to join forces to build relationships and generate solutions to barriers to advancement. At State Farm, for example, employees can choose from more than 100 ERGs. And at Cisco Systems, female employees benefit from a women’s action network ERG, which helps them develop as leaders and advance in their careers.

Groom Leaders Women aren’t likely to make it into the C-suites without critical profit & loss responsibility. Yet today, women fill only a small percentage of line positions held by corporate officers and top earners—those jobs with revenue generating or profit and loss (“P & L”) responsibility. Getting general management/line experience is critical to getting the top spot of an organization.  Experts say that once more women are in P&L positions, or lead revenue producing lines of business, we will to see more women being considered for senior management jobs.

Offer Work-Life Benefits The companies we recognize each year as the Working Mother 100 Best understand the importance of flexibility in helping working parents thrive. It’s hard to excel in your presentation if you’re upset that you’re missing your son’s big softball game. Allowing employees to work when and where they want are important steps to helping employees balance demands of work and family. Indeed, 100 percent of the 2009 winning companies offer telecommuting (compared with 45 percent nationwide) and flextime schedules (compared with 54 percent nationwide), while 98 percent offer job-sharing (compared with 16 percent nationwide), and 94 percent offer compressed workweeks (compared with 37 percent nationwide). The 100 Best still set the standard.