She combines personal anecdotes with hard data and compelling research to cut through the layers of ambiguity and bias surrounding the lives and choices of working women. She says thirty years after women became 50 percent of the college graduates in the United States, men still hold the vast majority of leadership positions in government and industry.

The 2003 Heidi/Howard study Sheryl cited was especially helpful. Two professors from universities in New York ran an experiment to test perceptions of men and women in the workplace. Half the students were assigned to read a story about a successful male venture capitalist called Howard. The other half read the same story but under the name of a female called Heidi. Although their accomplishments were identical the students said Howard came across as appealing and Heidi was seen as selfish and not “the type of person you would want to hire or work for.” Decades of subsequent research confirm the Heidi/Howard study. They show how success and likability are positively correlated for men and negatively correlated for women and how people are evaluated based on the stereotypes of gender, race, nationality and age. Sheryl believes this bias is at the very core of why women hold themselves back.

When a woman focuses on results rather than pleasing others, she's acting like a man. To protect themselves from being disliked, many women question their abilities, downplay their achievements and put themselves down before others can. Author Ken Auletta observed in his “New Yorker” article that for women “self-doubt” becomes a form of self defense.

Ken Chenault (CEO of American Express) told Sheryl he observed both men and women interrupting women at meetings and giving guys credit for an idea first proposed by a women. He said he now stops the meeting and points out the interruption. It makes participants think twice. Sheryl said she witnessed a similar incident at a business executive dinner. The guest of honor listened to and answered the men's questions politely but barked, “Let me finish!” and chastised the women for interrupting when they asked questions. A male CEO pulled Sheryl aside afterwards and said he noticed how the women were silenced.

Sheryl makes a compelling case for women to lean in, for being ambitious in any pursuit and to “Make their partner a real partner.” She says, “Career progression often depends upon taking risks and advocating for oneself – traits that girls are discouraged from exhibiting.” Women hold back in ways both big and small. They are hindered by the external barriers of society and the internal barriers that exist within themselves. They continue to internalize the cultural messages that say it's wrong for a women to be outspoken, aggressive, and more powerful than men. Lacking self-confidence and pulling back they lower their own expectations, do the majority of the housework and childcare, compromise career goals, and compared to their male colleagues, fewer aspire to senior positions. She says women’s progress in achieving leadership roles has stalled, their voices are still not heard equally especially in the decisions that most affect their lives.

Sheryl is aware there is no one definition of success or happiness. “We each have to chart our own

course and define what goal fits our lives, values and dreams.” Her goal is to help empower both women and men make the shift, person by person, to a more equal world.

Sheryl is the chief operating officer of Facebook and is ranked on Fortune’s list of the 50 Most Powerful Women in Business and as one of Time’s 100 Most Influential People in the World. In 2010, she gave an amazing TEDTalk where she described how women unintentionally hold themselves back in their careers. Her talk that encouraged women to “sit at the table,” seek challenges, speak their truth, take risks and pursue goals with gusto has been viewed more than two million times.

Sheryl's story is my story and I suspect the story of every woman.