Studies show that women are great negotiators — for other people. When bargaining for themselves at work, whether it’s a salary increase or a step up the corporate ladder, they’re not nearly as aggressive. In Women Don’t Ask: Negotiation and the Gender Divide, authors Linda Babcock and Sara Laschever explore not only why that is, but also its overall effects. For instance, Babcock says, a recent college graduate who accepts a $25,000-per-year job instead of negotiating for $30,000 will leave, over the course of her life, more than half a million dollars on the table. For an MBA who doesn’t negotiate, that number jumps to $1.6 million. What does this mean to their employers? Unhappy and unappreciated women who don’t advance through the company like their male counterparts may leave for other jobs, and attrition costs businesses $11 billion annually. Or in a worst-case scenario, women may sue over unfair practices.

While managers need to be aware of this disparity, women can help their own cause, Babcock says. They should realize the cost of wimpy negotiation, gather information on the comparative value of their jobs, and then practice their pitches before taking the plunge. And remember, that when in doubt, it never hurts to ask.