Five years ago, a 13-year-old named Ruby Karp sent a shockwave through the social media world when she wrote a blog post for Mashable headlined, “I’m 13 and None of My Friends Use Facebook.” Curmudgeon that I was even then, I pushed back on the notion that Facebook was “hurtling toward irrelevance,” “the next Yahoo,” or facing “the beginning of the end,” as various headlines had it. I pointed out that a 2013 Pew Internet survey that year had found Facebook was by far the most popular social network among teens. Facebook insisted that its own data also showed engagement among younger users holding steady, although its precise comments on that are probably best forgotten. Point is: Facebook still had the loyalty of the kids.

Two years later, Pew canvassed the teens and their social media use again, and again it found Facebook in the top spot. Engagement may have been slipping, but only one rival was even close—Instagram—and Facebook owned that one too.

That was the last word from Pew—until this Thursday. For the first time in three years, the nonprofit conducted a new survey of teens focused on their social media use. And it’s now clear that Karp and her friends weren’t aberrations. They were just ahead of the curve.

Facebook is no longer the dominant social network among teens, according to Pew’s survey of 743 U.S. residents aged 13 to 17, conducted between March 7 and April 10, 2018. In fact, it’s no longer even in the top three. (A Facebook spokesperson declined to comment on the survey.)

As the charts above show, YouTube, Instagram, and Snapchat have all surpassed Facebook in popularity. All three are used by more teens, and all three are more likely to be identified by teens as the social media platform they use most often. YouTube is used by the highest proportion (85 percent), while Snapchat is the one that the highest proportion say they use most often (35 percent). That loyalty factor is very good news for Snapchat, by the way, as it has been losing ground to Instagram along other metrics, such as user growth.

Does this mean YouTube is the new Facebook? Not exactly. Pew actually didn’t include YouTube in its earlier surveys, so we can’t know how it would have fared. And there’s good reason for not including it: Whereas Facebook, Instagram, Snapchat, and Twitter are all fundamentally social—that is, they’re places where most users post about their own lives—YouTube is more about passive consumption of content. It does have a social component, and users can of course post their own videos. But there’s a case to be made that it would fit more properly in a category with the likes of Netflix, Twitch, and Spotify.

Meanwhile, the survey does not include messaging services such as Whatsapp or iMessage, which could be considered rivals to Snapchat especially. This is not a full picture of what teens are doing with their screen time.

That said, it’s noteworthy that only 51 percent now say they use Facebook. That’s a dramatic drop from 2015, when 71 percent said the same. Even sharper has been the dropoff in those who identify Facebook as their most-used social platform: from 41 percent in 2015 to just 10 percent today.

The demographic trends aren’t working in Facebook’s favor, either, when it comes to advertising: Pew found that more of the teens still using Facebook are in lower income brackets, while its use among those whose households earn $75,000 or more is down to just 36 percent.

This still doesn’t mean Facebook is dying. It has become an essential Internet utility for much of the world, and remains so for many adults in the U.S., even as their offspring eschew it. It continues to grow, especially in developing countries.

It does, however, raise a warning flag for Facebook as the social network tries to fend off contrasting challenges from Snapchat and YouTube. Mark Zuckerberg last year announced a shift in focus from “passive consumption” of news and media to “meaningful interactions” between friends and family. But to the extent that teens remain a bellwether, it appears Facebook is losing ground on both fronts: The kids prefer YouTube for passive consumption, Instagram and Snapchat for self-expression and social interaction.

The large silver lining for Facebook, of course, is that it owns Instagram, and Instagram is doing just fine. But it should still concern the company that just 15 percent of teens say they spend more time on Instagram than other platforms. Facebook was built on hooking users at a young age and keeping them hooked as they grow up. Now it has to hope that young people who are growing up on rival platforms change their habits as they age.