Women occupy 40% of all managerial positions in the United States. But only 6% of the Fortune 500's top executives are female. And just 2% of those firms have women CEOs.

Those are the metrics being analyzed by Alice H. Eagly and Linda L. Carli in an incisive piece published by Conde' Nast Portfolio.

Observers have long blamed such numbers on the "glass ceiling," the notion that women successfully climb the corporate hierarchy until they're blocked just below the summit, but the problem may be more insidious. The inequity stems from discrimination operating at all ranks, not just the top, say Eagly and Carli.

Solving the problem not inly prevents unintended consequences.  It strengthens the  leadership style — characterized by innovating, building trust and empowering followers — that is ideally suited to today's business challenges.  The remedy is prescribed: Tackle the obstacles to women's progress, and you'll increase your firm's competitive prowess.

Eagly and Carli recommend these strategies for increasing the number of women in top positions in your firm:

Understand the Career Barriers Women Encounter

Extensive academic and government research studies identify these obstacles:

• Prejudice: Men are promoted more quickly than women with equivalent qualifications, even in traditionally female settings such as nursing and education.
• Resistance to women's leadership: People view successful female managers as more deceitful, pushy, selfish, and abrasive than successful male managers.
• Leadership style issues: Many female leaders struggle to reconcile qualities people prefer in women (compassion for others) with qualities people think leaders need to succeed (assertion and control).
• Family demands: Women are still the ones who interrupt their careers to handle work/family trade-offs. Overloaded, they lack time to engage in the social networking essential to advancement.

Intervene on Multiple Fronts

Because of the interconnectedness of obstacles women face, companies that want more women leaders need to apply a variety of tactics simultaneously:

• Evaluate and reward women's productivity by objective results, not by "number of hours at work."
• Make performance-evaluation criteria explicit, and design evaluation processes to limit the influence of evaluators' biases.
• Instead of relying on informal social networks and referrals to fill positions, use open-recruitment tools such as advertising and employment agencies.
• Avoid having a sole female member on any team. Outnumbered, women tend to be ignored by men.
• Encourage well-placed, widely esteemed individuals to mentor women.
• Ensure a critical mass of women in executive positions to head off problems that come with tokenism. Women's identities as women will become less salient to colleagues than their individual competencies.
• Give women demanding developmental job experiences to train them for leadership positions.
• Establish family-friendly HR practices (including flextime, job sharing, and telecommuting). You'll help women stay in their jobs while rearing children, allow them to build social capital, and enable them eventually to compete for higher positions. Encourage men to participate in family-friendly benefits, too (for example, by providing paternity leave). When only women participate, their careers suffer because companies expect them to be off the job while exercising those options.
• Give employees with significant parental responsibilities more time to show they're qualified for promotion. Parents may need a year or two more than childless professionals.
• Establish alumni programs for women who need to step away from the workforce. Then tap their expertise to show that returning is possible. Consulting giant Booz Allen, for example, sees its alumni as a source of subcontractors.