Lean In

performance as worse than it actually is, while men judge their own performance as better than it actually is. Assessments of students in a surgery rotation found that when asked to evaluate themselves, the female students gave themselves lower scores than the male students despite faculty evaluations that showed the women outperformed the men. 4 A survey of several thousand potential political candidates revealed that despite having comparable credentials, the men were about 60 percent more likely to think that they were “very qualified” to run for political office. 5 A study of close to one thousand Harvard law students found that in almostevery category of skills relevant to practicing law, women gave themselves lower scores than men. 6 Even worse, when women evaluate themselves in front of other people or in stereotypically male domains, their underestimations can become even more pronounced. 7
    Ask a man to explain his success and he will typically credit his own innate qualities and skills. Ask a woman the same question and she will attribute her success to external factors, insisting she did well because she “worked really hard,” or “got lucky,” or “had help from others.” Men and women also differ when it comes to explaining failure. When a man fails, he points to factors like “didn’t study enough” or “not interested in the subject matter.” When a woman fails, she is more likely to believe it is due to an inherent lack of ability. 8 And in situations where a man and a woman each receive negative feedback, the woman’s self-confidence and self-esteem drop to a much greater degree. 9 The internalization of failure and the insecurity it breeds hurt future performance, so this pattern has serious long-term consequences. 10
    And it’s not just women who are tough on themselves. Colleagues and the media are also quick to credit external factors for a woman’s achievements. When Facebook filed to go public,
The New York Times
ran an article that kindly reminded me—and everyone else—that I had “been lucky” and “had powerful mentors along the way.” 11 Journalists and bloggers rose up to highlight the double standard, pointing out that
The New York Times
rarely ascribed men’s success to having been lucky. But the
Times
didn’t say anything that I had not already told myself a thousand times. At every stage of my career, I have attributed my success to luck, hard work, and help from others.
    My insecurity began, as most insecurities do, in high school. I attended a big public school in Miami—think
Fast Times at Ridgemont High
—that was far more concerned with preventing fights in the halls and keeping drugs out of thebathrooms than with academics. When I was accepted into Harvard, many of my high school classmates asked me why I would want to go to a school filled with geeks. Then they would stop short, remember who they were talking to, and sheepishly walk away without waiting for an answer, realizing they already had it.
    Freshman year of college was a huge shock for me. First semester, I took a course called The Concept of the Hero in Hellenic Civilization, which was nicknamed Heroes for Zeroes. I didn’t have a burning desire to study Greek mythology, but it was the easiest way to fulfill the literature requirement. The professor began the first lecture by asking which students had read these books before. I whispered to my friend next to me, “What books?” “
The Iliad
and
The Odyssey
, of course,” she replied. Almost every single hand went up. Not mine. The professor then asked, “And who has read these books in the original?” “What original?” I asked my friend. “Homeric Greek,” she replied. A good third of the class kept their hands up. It seemed pretty clear that I was one of the zeroes.
    A few weeks later, my professor of political philosophy assigned a five-page paper. I was panicked. Five whole pages! I had only written one paper of that length in high school, and it was a year-long project. How could anyone write five pages in just one week? I stayed in every night, plugging away, and based on the time I put in, I should have gotten an A for effort. I got a C. It is virtually impossible to get a C at Harvard if the assignment is turned in. I am not exaggerating—this was the equivalent of a failing grade. I went to see my dorm proctor, who worked at the admissions office. She told me that I had been admitted to Harvard for my personality, not