At the Makery—a communal workspace for nascent start-ups in a light-filled loft in the Williamsburg section of Brooklyn—the atmosphere pulses with youthful exuberance. By day, the proprietors of Inlust (a video-based dating site), Small Girls Big Business (a fashion P.R. consultancy), and Jauntsetter (a travel website), among others, work at their laptops while singing along to Cee Lo's "Fuck You"; by night, they unwind with speed-texting parties. The Makery's mission, its 31-year-old founder, Matt Langer, announced on his Tumblr last August, is to create "an enriching, cross-pollinating environment where people making great things can make even better things when they're surrounded by others doing the same." Langer's rotating cast of ambitious young tenants—who pay $300 a month for a desk, Wi-Fi, and the privilege of mingling with others on the make—are driven by a new kind of entrepreneurial spirit. "We're having something of a renaissance right now," Langer says. "Services became cheaper, the cost of hitting the ground got lower, and that brought in investment dollars. At this point, the ball is rolling."

The act of striking out on your own is hardly a new phenomenon—it's the DNA of the American Dream, after all—but it might well be today's savviest career move. Although tech geeks may have laid the groundwork with platforms that can be utilized across industry boundaries, Silicon Valley is no longer the primary launching pad for emerging entrepreneurs. Around the country, there's a groundswell of can-do start-ups among artisanal food-makers, boutique retailers, even automakers, and the government is starting to take notice. In November, after the Ewing Marion Kauffman Foundation released the findings that "startups and young firms . . . account for nearly all net job creation in the United States," the Senate unanimously adopted a resolution declaring the first-ever "Global Entrepreneurship Week." It's no wonder, then, that the boundaries of age are also falling. "There's a stereotype being formed—probably by Mark Zuckerberg—that everyone who's creating a company is 25," says John Borthwick, the CEO of Betaworks, which makes seed investments in start-ups in what the company calls the real-time social web space. "But the majority of new entrepreneurs aren't right out of school." And they're not sad sacks who discovered the virtues of self-employment after being downsized. In fact, they are closer in spirit to the partners of Sterling Cooper Draper Pryce on Mad Men, who started their own ad agency after being manipulated by the corporate schemers who were buying and selling them like commodities. Despite being separated by decades of social and technological upheaval (not to mention the gulf between fiction and reality), we are motivated by the same impulse—not so much to stick it to the Man, but to be a better version of him. "If the Internet makes these new businesses possible, well, so does indoor plumbing," says Clay Shirky, the author of Here Comes Everybody: The Power of Organizing Without Organizations. The new entrepreneurs, he says, "are simply using the residue of that revolution, on their way to doing the things they most care about."

Langer, a natural-born connector, has made a career (and a few killings) out of being a serial entrepreneur: He joined online-game designer Conduit Labs in 2008 and cashed in his equity when it was bought two years later for an undisclosed sum by Zynga, the world's largest social-game developer. By then he had already helped build Hot Potato, a New York-based "check-in" service that launched with $1.42 million in seed funding and was reportedly bought by Facebook for seven times that amount less than a year later. When Hot Potato moved out of its Williamsburg loft, Langer used a fraction of his payout to take over the lease and start the Makery. "The way I look at these things is: In the age after Enron, to go out and start your own business, raise money, turn it into something bigger, create livelihoods for people—that's a great thing. Mark Zuckerberg created 1,500 jobs with something he started in college—that's probably one of the noblest things about the whole adventure."

What Langer has built is a landing spot for those who have made the leap from corporate culture into entrepreneurship. One of the Makery's tenants is Chris Carella, 32, who runs Super+Fun (a social funware company) with his wife, Becky. "We have this culture of bringing people in, and that's great for investors because they can meet with half a dozen companies at once," he says. "Then, maybe twice a week, I'm getting a coffee with someone new, exchanging skill sets and contacts. They want to hear about what you're working on, give feedback, get advice."

For John B. Rogers Jr., the entrepreneurial leap represented a total change of culture. Rogers hadn't been frustrated by the drudgery of the office; he had his moment of clarity during a tour of duty with the U.S. Marine Corps in Iraq. "I was volunteering for a miserable job that ostensibly had great national import, but I could be back in America also doing something worthwhile—and not getting shot at," Rogers says. After returning to civilian life and getting an M.B.A. from Harvard, Rogers, a car lover, considered working for one of the Big Three, but he didn't want anything to do with their "environmentally unfriendly, uncool" methods. Instead, Rogers, now 37, drummed up $7 million from 40 individual investors and founded Local Motors, which produces made-to-order cars, using customer input and elbow grease (yes, you build your own set of wheels), in Arizona. He has ambitious plans for a national network of "microfactories," each of which will produce models that are environmentally appropriate for local climates, but knows he is still a long way from moguldom. "You can start to doubt yourself late at night," Rogers says, "but the thing that brings me back is a very simple promise: We want to make cool cars that people want to buy. When I think about that, all the other stuff melts away."