A few years ago, if you had asked me about Silicon Valley's gender imbalance, I would have wondered what planet you were from. I believed it was a perfect meritocracy that was open and diverse. My research had documented that the majority of Silicon Valley's startups were founded by immigrants and that powerful and inclusive networks gave it a global advantage.

That was until I moved to Silicon Valley and started noticing the gender composition of technology companies. I learned that it was a boys club. Even the immigrants left women out of their networks and support systems. I have since researched the problem extensively and crowd-created a book about the challenges that women have faced and how they are surmounting them. For this book, Innovating Women, which will be released on Sept. 9, hundreds of women shared their stories and the secrets of their success.

Here are some of the most common challenges that the women said they faced:

1. Preconceived and unchallenged cultural notions of gender: The women often found themselves to be either the only woman, or one of very few women, sitting at the decision-making table. Many also said they had been mistaken for the "coffee-getter."

"On my very first job as a scientist, I arrived early at work to set up my presentation. Just then, the big-big-big boss arrived and asked me where the coffee was located and, wherever it was, could I get some for him," said Susan Baxter, executive director of the California State University Program for Education and Research in Biotechnology.

Sunny Bates, CEO of Red Thread, shared a conversation she had had with a new mother: "When she had a girl, everyone was, 'Oh she's so pretty, she's so beautiful,' and all these dresses came. Then when she had a boy, it was all about the San Francisco Giants and the future president of the United States. No one once said, 'Oh he's beautiful.' "

2. Negative stereotypes and discouragement: Emily Fowler, co-founder and vice president at HeroX, recalls her high-school experiences: "The stereotypes were your traditional comments like 'nerd,' 'dork' 'loser.' Oh, and my personal favorite was 'lesbian.' Fortunately, I didn't care and I had a sharp enough mouth at a young age that when people -- and by people, I do mean guys--said that to me, I would just retort with, 'First of all, being a lesbian is not an insult. Secondly, being smart or curious doesn't make me a lesbian. What did you learn at football camp?' Girls teased me as well and that was a bit hurtful. Mostly, they were concerned that I would be seen as a lesbian."

Pam Barry, co-founder and chief operating officer of Customerforce.com, said: "My father suggested I had the aptitude to be a computer programmer. I was told by my career-guidance counselor that I would be lucky if I could get a job as a computer operator, never mind programmer. My mother was furious with her, and my parents set out to help prove her wrong. At age 17 I took two aptitude tests for two different organizations and was offered a position with both as a programmer. Chose one of the offers and dropped my applications for university."3. Educational bias against women and girls: The Bayer Corporation ran a survey in 2010 that found that 40% of women and ethnic-minority chemists and chemical engineers had been discouraged from pursuing their field, most often by college professors. The survey respondents identified three top factors that helped keep women and minorities from majoring in STEM (science, technology, engineering and mathematics): lack of quality educational programs in those fields in poorer school districts (75%); persistent stereotypes that say STEM isn't for girls or minorities (66%); and financial issues relating to the cost of education (53%).

4. Lack of resources and role models: Whether in finding female role models or in obtaining funding, women have always been at a disadvantage. Ann Winblad, who has become one of Silicon Valley's leading venture capitalists, recalled how she started her financial and accounting software firm, Open Systems Inc., in 1974, just 13 months out of college, with a $500 loan from her brother. Believing in her ability to write software, she convinced three friends to go on sabbatical or quit their jobs to join her. She negotiated free access to the computers of a local computer reseller in the evenings, and persuaded a bank to lend her $25,000 and her teammates to accept salaries low enough to allow them to qualify for food stamps.

Sian Morson founder of Kollective Mobile, said of the lack of role models: "Black women at the agencies I worked at were in [human resources] or some other administrative or supporting roles ... No one took me under their wing and showed me the ropes, and if they did they looked more like James than like me. I carved my own path up the ladder of success, buoyed by the beliefs instilled in me by my family and by having a strong sense of self."

5. The age-old question, "Can women have it all?": Balancing work and home life was one of the liveliest conversations on our discussion boards. Consultant Anne Hartley summarized the challenge by saying: "Until we get completely comfortable with 'dads' in roles that have been traditional 'mom' roles as the norm, young women who get all the right education and then retreat will continue to feed the gap we are trying to address. When society and cultural norms evolve to where women do not feel that they must 'choose' their place in the family over fully applying their education and themselves for the benefit of humanity or that they are 'bad mothers' to manage their career at the same level of importance as their family."

Women are now achieving extraordinary successes. And this is causing the face of Silicon Valley to change, as I will detail in my next piece.

Vivek Wadhwa is a fellow at the Rock Center for Corporate Governance at Stanford University, director of research at the Center for Entrepreneurship and Research Commercialization at Duke's engineering school and distinguished scholar at Singularity and Emory universities. His past appointments include Harvard Law School and University of California Berkeley.

Innovating Women will be released on September 9.