Men and women are still treated unequally in the workplace. Women continue to earn less, on average, for the same performance, and they remain underrepresented in top jobs. Research has shown that both conscious and subconscious biases contribute to this problem. But we’ve discovered another, subtler source of inequality: Women often don’t get what they want and deserve because they don’t ask for it. In three separate studies, we found that men are more likely than women to negotiate for what they want. This can be costly for companies—and it requires management intervention.

A version of this article appeared in the October 2003 issue of Harvard Business Review.