Facebook made two seemingly unrelated announcements in June. The first was that the social network now has 2 billion monthly users, or more than half of Internet users globally. The second was that it was changing its mission statement for the first time since Facebook was founded 13 years ago.
The social network has endured a firestorm of criticism in the past year, between the proliferation of fake news and unexpected consequences from its new streaming service, Facebook Live, including but not limited to the live-streaming of sexual assaults, murders, and police brutality.
The company, joining the ranks of Fortune’s Global 500 for the first time this year at No. 393, recently declared that its focus would shift from making “the world more open and connected” to giving “people the power to build community and bring the world closer together.”
These two landmark moments have one woman in common: Naomi Gleit, whose official title is Facebook’s vice president of social good, but whom CEO Mark Zuckerberg recently described as “the woman in charge of growing our community.”
Gleit has worn many hats at Facebook (fb) since she joined in 2005. She visited Facebook’s Silicon Valley offices every week after graduation from Stanford University until she became the company’s 29th employee.
“I know that sounds a bit weird, but I was adamant, and I had extreme clarity that Mark was going to be an important person,” Gleit says. “I almost had a spiritual belief.”
Today she’s Facebook’s longest-tenured employee—after its CEO, of course.
While vice president of social good, Gleit has also served as a member of the company’s eight-person core growth team. For the past decade, the team has been focused on getting more people to join Facebook. In 2006 this was as simple as opening up the college-only site to high school students. Then to the U.S. population at large. As the site expanded, so did her duties at the company.
To acquire users, the team turned to data, dissecting the pain points of the registration process and daily use at the most granular level. Armed with hard numbers, they were able to dedicate resources to translating the site into 100 languages and to creating a “Facebook Lite” for users in developing countries, who have to contend with slow Internet speeds and basic mobile devices.
In corporate speak, Gleit’s role is to “do good and build tools for people to do more good.” For everyday users, this can be seen with features like Safety Check, a tool that lets people in an affected area check in as safe (and notify their networks). She also led the charge in creating Facebook’s fundraising tool, making it easier for nonprofits and individuals to raise money on the platform.
Tapping Gleit—who previously has been tasked with high-priority projects like revamping privacy settings—to lead the social good team is illustrative of Zuckerberg’s priorities. In addition to publicly pledging in 2015 to give away 99% of his wealth, he has been trying to position Facebook as a medium for making the world a better place—now explicit in the new mission statement.
“We have to build a world where everyone has a sense of purpose and community,” he said in June at Facebook’s Communities Summit. “We have to build a world where we care about a person in India or China or Nigeria or Mexico as much as a person here.”
For many Facebook users, this kind of talk is at odds with the headstrong reputation Zuckerberg acquired in the 2010 film The Social Network. Gleit says she’s seen Zuckerberg’s altruistic side since joining Facebook. “I already saw this intention,” she says. “I don’t why, but at 21, Mark felt that he needed to save the world.”
Zuckerberg might be starting closer to home first. After criticism flew that Facebook didn’t do enough to curb fake news during the 2016 U.S. presidential election, the CEO announced he would tour all 50 states to take a pulse on the current political climate. Popping up at small businesses and town halls seemingly without notice, his trip has sparked speculation about a future presidential run.
Back at Facebook, Gleit has her work cut out for her. The biggest challenge now is reaching the next billion users—and the way to do that will look nothing like the way Facebook recruited its first or even second billion, likely because of one barrier: Internet access. Less than half the world’s population can currently get online. To that end, the company launched Internet.org in 2013, an initiative to provide low-cost, high-bandwidth Internet in developing countries. But critics quickly argued on net neutrality grounds that the connections might prioritize Facebook’s services.
Meanwhile, a major focus of the social good team is figuring out how Facebook Live can best be used for good. Gleit says she has already seen success. Viewers of the One Love Manchester benefit concert, for example, in the aftermath of a terror attack on the U.K. city, collectively donated nearly half a million dollars via Facebook.
“Tech is not inherently good or bad,” Gleit says. “We want to maximize the good and minimize the bad.”
A version of this article appears in the Aug. 1, 2017 issue of Fortune with the headline “Facebook’s Secret Weapon.” That version incorrectly stated that Facebook has been translated into 180 languages. It has been translated into 100.