Women systematically underestimate their own abilities. If you test men and women and you ask them questions on totally objective criteria, like GPAs, men get it wrong slightly high, and women get it wrong slightly low. Women do not negotiate for themselves in the workforce. A study in the last two years of people entering the workforce out of college showed that 57% of boys entering or men, I guess, are negotiating for salary, and only 7% of women. And most importantly, men attribute their success to themselves and women attribute it to other external factors. If you ask men why they did a good job, they'll say. I'm awesome. If you ask, obviously. Why are you even asking? If you ask women why they did a good job? What they'll say is someone helped them they got lucky, they worked really hard. Why does this matter? Boy, it matters a lot. Because no one gets to the corner office by sitting on the side, not at the table, and no one gets the promotion if they don't think they deserve their success, or they don't even understand their own success.