The blinds are all closed to the modest new #NeverAgain office in a nondescript strip mall. The location is closely guarded, and the old tenant’s name is stenciled on the window. You knock and announce yourself to get in. Expect a wisecrack back, and a regular flurry of silliness inside. The tiny conference room buzzes with the vibe of an S.N.L. writers’ room. Saturday’s massive March for Our Lives will gobble up the headlines—that’s the point—but this bubbling ideas lab, both physical and virtual, points to the movement’s long game.

It was social media that launched #NeverAgain on day one, and social media is the key to its future. Ever since a gunman opened fire at Marjory Stoneman Douglas High, in Parkland, Florida, killing 17 people between the ages of 14 and 49, this band of grief-stricken but savvy and highly determined students and alumni has seized control of the gun debate in the United States, capturing the attention of Congress, the N.R.A., and even the spectacularly narcissistic POTUS himself. Now, they are pumping out clever, shareable content on Twitter, Instagram, and Snapchat, and prepping a YouTube launch. “That’s where our generation lives,” said #NeverAgain’s self-described memes man, Dylan Baierlein, a recent graduate of Douglas High who has been working quietly behind the scenes.

“What a lot of my generation does is basically come home from school, eat a snack, and watch whatever’s in their subscription box from YouTube,” Douglas High senior David Hogg told me. “That’s how they get a lot of their information.”

Saturday’s March for Our Lives in Washington, D.C., will be accompanied by more than 800 sibling marches around the country and the world. “We just got our first African march,” Matt Deitsch, told me last week. Deitsch is another recent graduate and the movement’s community outreach director. “We had scientists in Antarctica say they’re going to officially put one together. So we’re in every continent.” In Washington, the permits estimate a crowd of 500,000, but the group expects to blow that away. “The collected data shows over a million people, and a lot of people haven’t been RSVPing,” Deitsch said. “It’s going to be overwhelming.”

Then what? For five full weeks, they have held the media’s attention—longer even than Columbine. But the march feels like a climax to their crusade. What happens after the media drifts away?

You mean old media, Deitsch said: “We’ve already established our platform.” The broadcast networks’ cameras may have built the #NeverAgain following, but its members’ own cameras have greater pull now. Ten million people watched co-founders Cameron Kasky, Emma González, David Hogg, Jaclyn Corin, and Alex Wind on 60 Minutes Sunday night, but the group believes they beat that themselves online most days. González already has 1.2 million Twitter followers for an account begun after the attack. Together, Hogg, Kasky, and junior Sarah Chadwick have another 1.1 million, and that number is growing fast. Twitter has been the group’s biggest platform, but they’re cultivating followings on the other three services.

Douglas High junior Cameron Kasky famously started #NeverAgain by gathering vocal, charismatic, and talented classmates at his house, culminating in a day-long slumber party over the first weekend. About 20 students make up the core group, with Kasky, González, Hogg, Corin, and Wind at the helm. But Kasky broadened the talent pool by reaching out to a few recent drama grads with exceptional media skills. Dylan Baierlein and Matt Deitsch are key backstage players, integral to the content-creation brain trust.