Sam Grobart says choosing the right HEADLINE can make the difference between 1 million views and 15 million:

Doctors gave Zach Sobiech bad news just after his 17th birthday last year: His rare bone cancer had progressed so far that he had only a year to live. In December, Sobiech posted a music video of Clouds, a song he wrote and recorded about struggling with the disease. He became the subject of a short online video documentary, which garnered tens of thousands of views after being featured on FoxNews.com and People.com. Sobiech died on May 20.

Then the editors at viral-media site Upworthy saw the documentary. They repackaged it with the headline “This Kid Just Died. What He Left Behind Is Wondtacular.” Since then more than 15 million people have watched the documentary on Upworthy, which aggregates and popularizes videos and other online content. Sobiech’s song went to No. 1 on Apple’s iTunes Store, and a link Upworthy put next to the video raised more than $300,000 for cancer research. “The whole Internet heard his story,” says Upworthy co-founder Peter Koechley.

Upworthy didn’t produce Sobiech’s music video. It had no hand in the documentary. All it did was slap a new headline and some sharing tools on an existing piece of media, and promote it among its subscribers, who included the video in their own feeds on social media sites such as Facebook and Twitter.

The video, Upworthy’s most successful post to date, embodies the company’s goal: to promote meaningful stories by using social media to reach as many people as possible. To most, viral videos mean silly shorts about cats, but Upworthy, founded by The Onion veteran Koechley and MoveOn.org’s Eli Pariser, boasts of its higher values. “People get viral content wrong,” Pariser says. “They imagine that the reason people share stuff is to have a laugh. But a huge part of sharing is being passionate about something, about shedding light on what really matters.”

The 25-employee site garnered visits from 26 million people in May, its best month so far. At 16 months old, Upworthy is getting more visitors than Us Weekly’s site,CNBC.com (CMCSA), or Gawker, according to data from Web-ranking firm Quantcast. “They’re starting from a place of authenticity,” says Michael J. Wolf of media consultant Activate. “Upworthy is about what matters most.”

The conventional wisdom is that viral pay dirt requires volume. Whether the content is being created or repurposed, sites such as BuzzFeed and Gawker produce dozens of posts a day. Upworthy staffers, by contrast, are told to find the most compelling content available, then spend most of their time thinking about how to present it. “Our curator who gets the most traffic barely publishes six things a week,” Koechley says.

Upworthy’s presentation mostly involves headline writing and rewriting. Most headlines are revised 25 times before publication, a fine-tuning strategy inspired by Koechley’s Onion days. “The headline is our little newsboy crying out in a crowded Facebook feed,” he says. For the post on Sobiech’s video, staffer Adam Mordecai tested 79 options. The “wondtacular” headline wound up on top because words you’ve never seen before catch your eye, Koechley says. “We’d determined that, had Adam not optimized that headline, that post would have gotten maybe 1 million views—not 15 million,” he says.