It's a fair question for Marshall Herskovitz and Ed Zwick, the Emmy-winning writing-producing-directing team: Why are two fiftysomethings—the guys who brought us the '80s TV series Thirtysomething—creating and bankrolling a social network and an online TV program aimed at twentysomethings?

Back in 2004, Herskovitz and Zwick made a pilot for a series then called ¼life for ABC. The network passed. Last year, the pair talked to ABC again about reworking the show but couldn't agree on its direction. So Herskovitz and Zwick went to their agents at Creative Artists Agency for help plotting a strategy to resuscitate the project online, as Quarterlife. The outcome? The producers are breaking the cardinal rule of Hollywood: They're financing the experiment themselves.

Quarterlife debuted on MySpaceTV on November 11 with the first of 36 eight-minute episodes. The show purports to be of TV quality (read: expensive to produce) and centers on Dylan, a young woman who keeps a video blog (itself called Quarterlife) about her travails in life and love. Herskovitz and Zwick will split advertising revenue 50-50 with MySpace, which is getting the content for free. (The series will also be shown on Quarterlife.com, and Herskovitz and Zwick will keep all ad revenue from that stream.) "We're spending a lot more than we necessarily know we're going to be able to recoup," Zwick says, declining to be more specific. "Will advertisers be willing to support that? It's a big gamble."

If a Web series were all the duo was up to, little would distinguish them from other creative folks—Seth MacFarlane (Family Guy) and Matt Stone and Trey Parker (South Park), to name a few—who have recently forged deals to take their content to the Web. But Herskovitz and Zwick see their new venture as a jumping-off point for something larger: a Web community that encourages members to display their creativity. The hope is that fans of the fictional Quarterlife series will visit Quarterlife.com and decide to stay.

Will Quarterlife.com succeed in stealing users from Facebook and its own partner, MySpace? If it does, it will join a growing field of niche networks (such as Eons.com for baby boomers) that are trying to chip away at the behemoths. "The great myth about most social networks is that they're communities," says venture capitalist Paul Kedrosky, who writes the blog Infectious Greed. "Everybody on them has nothing in common—other than being on them."

Zwick knows that some will question whether a site created by guys in their third quarter of life will appeal to an audience just entering its second. "But we were in our forties when we did My So-Called Life," he says of their series on teens. "How old was Salinger when he wrote about Holden Caulfield?"