When Sara Horowitz founded the Freelancers Union in 1995, there was already evidence that the structure of people's work lives was changing.

Publishing and media jobs had started to move to more project-based work. Horowitz, a union organizer and labor lawyer by training, assumed that other industries would follow. As an expert in labor unions, she thought “it was really important to start thinking about how people [can] come together” to change laws and public policy, so that freelancers can obtain job-related “benefits—and community.”

Today, the Brooklyn-based Freelancers Union boasts nearly 300,000 members, having quadrupled in numbers in just seven years. Freelancers in the union include technology consultants, copywriters, web designers, visual artists, business-development consultants, journalists, and professional coaches. They live all over the country, with concentrations in New York, New Jersey, and California.

Besides offering freelancers a sense of camaraderie, the union offers: its own health-insurance plan; networking and education events; free advice on the freelance business, dispensed through its blog and social media; and discounts on dental, disability, and life insurance, through vendors vetted by the union. For New York City members, the union also runs two primary-care health clinics—requiring no co-pays—and community spaces with free yoga classes. Best of all, membership is free; the union supports itself with a fee on health insurance and other services it provides.

The intention is to give freelancers perks they'd receive if they held full-time jobs, which fewer and fewer workers do, sometimes involuntarily. Rather than mourn an era's passing, Horowitz says, the Freelancers Union has tried to forge a new way to think about supporting workers in the gig economy. “What happens … is that people start living their lives,” she adds, “and they've started to put together their lives in really different ways.”

Thirty-nine-year-old Xavier Fan is in this vanguard of unionized freelancers. Fan went independent, by choice, roughly nine years ago, working as both a technology consultant and an actor from his home in Brooklyn. Originally, he joined the Freelancers Union to buy health insurance as well as liability insurance to protect against lawsuits, purchased through one of the union's designated vendors. He has also attended union-sponsored events on topics such as taxes, branding, and the logistics of getting paid. As a freelancer who typically works from home, Fan says, “some of the socialization aspect of working full-time in an office isn't there,” and the union's gatherings give him a chance to mingle. He also appreciates the union's lobbying on behalf of its members.

Networking and insurance also drew Gina Bruce, a 59-year-old copywriter now in Mt. Kisco, New York. As one of the union's original members, at times she has leaned on the group for leads on jobs, advice on freelancing, and health insurance. It has also given her a sense of professional community. “Freelancers are wanderers,” Bruce says. “We're mostly sole proprietors.” She finds the union important “because it gives freelancers a forum to talk about what is going on.”

Bringing freelancers together is an urgent task in today's economy, says union leader Horowitz, citing a “massive acceleration” of their numbers in the past few years. “There is kind of a consciousness,” she adds, “that people will freelance at some point in their lives.”

It is hard to find an accurate estimate of the number of freelance workers who participate in the so-called sharing economy, which is dominated by technology companies that rely on freelancers for much of their labors—Uber, Lyft, Postmates, Instacart, and the like. The U.S. Government Accountability Office estimated this spring that the freelance workforce ranges anywhere from less than 5 percent to more than a third of the nation's workforce, depending upon how freelance workers are defined. GAO found that freelancers were more likely to be young, Hispanic, and relatively poor.

A study commissioned by the union and Elance-oDesk, a company that connects employers to suitable freelancers, puts the number at the higher end—at 34 percent of the workforce, or roughly 53 million people, counting full-time freelancers, people with second jobs, and temporary workers hired for a particular project.

In any event, experts say, the ranks of freelancers will continue to grow, which drives Horowitz toward her long-term union goal: to develop a new type of social safety net for freelancers. While the sharing economy offers workers the boon of flexibility, it does little to protect them if things go wrong—no unemployment benefits if the work dries up or workman's compensation if they're injured. Often, they pay higher taxes—both the employee's and employer's contributions to Medicare and Social Security. As for long-term security, forget about it.

“We have left all of the risk of the flexible work on workers,” Horowitz says. “It is a problem for human beings—how do you plan your life? It is also a really big problem because the tax rolls will get barer and barer, as you don't have a middle class to tax widely.”

Rethinking the social safety net would blur the distinction between full-time employees and freelancers, so it's no longer an all-or-nothing proposition. Instead of waiting for the federal government to plot a strategy, Horowitz figures labor unions or nonprofit groups or social-minded businesses can lead the way, maybe by joining with a city on a pilot project. “I don't care if people are independents or Republicans or Democrats, conservatives or radicals,” she says. “We are … finding our allies.”