SAN FRANCISCO (AP) — Facebook CEO Mark Zuckerberg spoke out publicly for the first time Monday in favor of immigration reform, an issue he's been working on behind the scenes for several months.

The 29-year-old billionaire made his remarks in San Francisco at the debut screening of "Documented," an autobiographical documentary by activist and journalist Jose Antonio Vargas.

Wearing his trademark hoodie and sneakers, Zuckerberg disputed the notion that he and other Silicon Valley leaders are just trying to secure more H1B visas for high-tech workers.

"This is something that we believe is really important for the future of our country — and for us to do what's right," Zuckerberg told several hundred attendees, including House Minority Leader Nancy Pelosi and San Francisco Mayor Ed Lee, at the Yerba Buena Center for the Arts.

Zuckerberg and his former Harvard University roommate Joe Green recently founded the organization Fwd.us to advocate for a pathway to citizenship for nearly 11 million immigrants living in the U.S. illegally. But Monday was the first time Zuckerberg spoke about the issue in public.

The Facebook Inc. founder said he first became aware of the need to change the immigration system while volunteering to teach a class on entrepreneurship at a Menlo Park school. Many of the students had been brought into the U.S. illegally.

"No matter where they were born, (these students) are going to be tomorrow's entrepreneurs and people creating jobs in this country," he told the audience. "These are issues that don't just touch our part of the industry, but really touch a whole country."