Sheryl Sandberg, Facebook’s chief operating officer, said the world’s biggest social media company is obligated to promote communities and connections among people — and do so in a positive way.

With about 1.9 billion monthly users, “we have a responsibility to build things that are good” and which promote “kindness and empathy,” said Sandberg, speaking at the Cannes Lions advertising and media conference Wednesday.

She added, “That’s why I went to work for a 23-year-old” in 2008 — CEO Mark Zuckerberg — “because we shared the same values.”

Sandberg alluded to Zuckerberg’s manifesto for the company released in February, saying the Facebook mission is broader than just minting money: “We are bringing the world closer together. In a world that has so many challenges… we are still a world of individuals.”

That said, Facebook has faced challenges as it tries to become more of a force for social good around the world. The company has been battling the spread of fake news in a more concerted way since the 2016 U.S. presidential election, and it’s taking steps to better respond to acts of violence and suicide that have been broadcast on Facebook Live. Meanwhile, numerous studies have found that prolonged use of social media like Facebook can lead to depression and loneliness.

Facebook has a complicated set of internal guidelines for moderators to deal with objectionable content, which the company has acknowledged it hasn’t always gotten right and is continuously trying to improve.

Sandberg, as an example of Facebook’s support for the creation of communities, called out the Option B group on the platform, which has 350,000 members. The support group is inspired by Sandberg’s recent book “Option B: Facing Adversity, Building Resilience, and Finding Joy” about coping with her husband’s death two years ago. Sandberg said she’s found tremendous help from people participating in the Option B group about dealing with grief.

“There are days when I need that attachment to people… who have been through that themselves,” she said. “Together, we are less alone.”

Sandberg also recounted Facebook’s hard shift five years ago to mobile, when Zuckerberg pushed senior execs to become a mobile-first company.

At the time, “we had no mobile revenue — not a little bit. None,” Sandberg said. “We went hard… We absolutely prioritized newsfeed and mobile revenue over desktop revenue.” Today, she said, Facebook has a “Super Bowl-size audience” every day on mobile.

Sandberg, one of the most powerful businesswomen in the world, also addressed questions of gender and racial diversity. She said one of the things she’s most proud of is helping to create Cannes Lions’ Glass Lion award, which recognizes advertising confronting gender inequality or prejudice.

Sandberg appeared on the panel “Building Community Through Creativity on Mobile” along with Jonathan Mildenhall, CMO of Airbnb.

Mildenhall, for his part, said Airbnb breaks the rules of creating a global brand: “Every single Airbnb experience is different. For us, it’s not about standardizing our products — it’s about standardizing human values.”

Panel moderator Colleen DeCourcy, global chief creative officer at Wieden + Kennedy, commented about Facebook and Airbnb: “It’s hard to think of two companies with missions or ambitions that are bigger or more relevant for the world we live in.”

Sandberg, before joining Facebook in 2008, was Google’s VP of global online sales and operations at Google. Before that she served as chief of staff for the U.S. Treasury Department under President Clinton and worked as a consultant with McKinsey & Co. and as an economist with the World Bank.