When Ruchi Sanghvi arrived for her first job interview at Facebook's headquarters, no one was there.

It was the fall of 2005 and when she reached the startup's graffiti-covered offices in downtown Palo Alto at noon, they were empty. Two hours later, she was still waiting. At 3 p.m., someone finally arrived to interview her -- the engineers had been up all night coding and slept in, she learned later.

Sanghvi was undeterred. Impressed by the place, the people, and the product, which she had spent hours using as a student at Carnegie Mellon University, she became Facebook's first female engineer, one of the first 10 engineers hired by the company.

Sanghvi's five-year career at Facebook underscores the meritocratic nature of the startup world, where a bright, young engineer like Sanghvi, who was raised in the industrial town of Pune, India, and didn't regularly use a computer until her freshman year of college, could play a key role in shaping one of the world's most influential web companies. Yet her experience also sheds light on the challenges female engineers faced then -- and still face -- in a male-dominated field. Sanghvi's story illustrates that despite all the talk of equality between the sexes, women often grapple with a unique set of difficulties when it comes to finding role models in the engineering field and making inroads into what she called "the boys' club."

During her tenure at Facebook, Sanghvi not only watched the company explode into a global network with a population greater than that of the United States, but also built the social network's most defining features. She launched News Feed, which radically changed the Facebook experience by putting friends' online activities front and center on the site; Platform, an update that allowed third-party developers and entrepreneurs to build apps on Facebook; and Connect, which made it possible for people to link their Facebook identities and friends to almost any site on the web. The products she developed helped propel the site forward and also rewrote the rules of the web, eroding anonymity on the Internet and ushering in a new age where peoples' real names were attached to everything they did online. Sanghvi describes this connection between offline and online identities as the next big idea in tech, one that will reshape everything from e-commerce to health care.

"Facebook has woven itself into the fabric of our lives and the foundation of the Internet," Sanghvi said. "I think everything will be redefined because people are using their real identities on the Internet."

Sanghvi said she was used to being the odd woman out -- she was one of five female students out of 150 in a course in the Electrical Computer Engineering department -- and at Facebook, she again found herself on a team with only a handful of female engineers.

Though she looks back fondly on her time at Facebook and describes it as "one of the best companies to be working at right now," she said her male co-workers enjoyed a certain camaraderie that she could not match or fully penetrate.

"It was difficult to break into the boys' club," Sanghvi said. "I wish that females had a similar culture or support network."

Sanghvi said the male engineers on her team created a "brogramming page," presumably only for the Facebook "bros" who were programming. She recalls having to change her working style to adapt to the "aggressive" environment, a shift she said affected how she was perceived.

"Engineers are either aggressive or passive aggressive. You need to just dive straight into it, and sometimes there are social repercussions because of it," Sanghvi explained. "The impression that people had of me was that I was really harsh, hard-edged, brusque and to the point. All of that happened because I am a woman, and I was acting in that kind of environment."

Facebook declined to disclose what percentage of its current total staff and engineers are female. The company does not have any affirmative action programs or quotas in place to attract female engineers, though Facebook supports and funds interest groups, such as Facebook Women or Women Engineers, that its employees create.

"Increasing the number of women in the tech sector is hugely important to Facebook," a Facebook spokeswoman said. "We want our company to reflect the diverse global community that we serve."

Facebook COO Sheryl Sandberg has also been an outspoken advocate for increasing the number of female leaders.

"Men run the world," Sandberg said in a May 2011 commencement address delivered at Barnard College. "We need women at all levels, including the top, to change the dynamic, reshape the conversation, to make sure women's voices are heard and heeded, not overlooked and ignored."

To Sanghvi, increasing the number of women in tech requires not only HR initiatives, but also having more female role models in engineering, computer science and other technical fields.

"Kids in college often look for mentors and role models to model their careers after, and women don't have the equivalent of a Steve Jobs or Bill Gates," Sanghvi said. "I think it's a self-perpetuating loop."

She also noted that women must ultimately be proactive about choosing their fate, and shared what she said is the most important lesson she's learned thus far in her career: "If I don't ask for something, I'm not going to get it."

Even as she is candid about the challenges she faced at Facebook, Sanghvi, who left in 2010 to start her own company, Cove, praised the tech industry for consistently rewarding excellence and ability above all else.

"It may not be a meritocracy, but it is the closest thing to a meritocracy in the working world,” she said. “I think that itself is very powerful."

Women in Tech, a series from HuffPostTech, showcases innovative female pioneers, from CEOs and scientists to entrepreneurs and engineers, who are changing the way we think about and engage with technology. Read more interviews and profiles from the series here