LOS ANGELES — When a group of workers at the video-game maker Riot Games staged a three-hour walkout in May over the company’s handling of sex discrimination accusations, they had help from a labor organizer named Emma Kinema.
Ms. Kinema doesn’t work for a union, but she is part of a grass-roots wave of labor activism, filling voids where traditional unions lack a presence. She volunteers for a group called Game Workers Unite while holding down a full-time job, subsidizing her endeavors by soliciting online donations.
Workers in industries like education, hospitality and technology are growing more assertive, engaging in strikes and informal walkouts at levels unseen in decades and taking part in new organizing efforts. And that should give unions, hobbled by years of legal setbacks and contending with unfriendly policies in Washington, reason for optimism.
“I’m exhausted,” Ms. Kinema said. “We could have 10 times the organizing capacity, 10 times the organizers, 10 times the experienced people, and there would still be an infinite amount of work to be done.”
The question is whether traditional unions can harness this energy and reverse their long-term membership decline, from about one-third of the work force in the 1950s to about one-tenth today. In some cases, unions have kept their distance unless workers first commit to becoming members. In other cases, workers say unions have taken action without giving them a sufficient voice.
The biggest labor federation, the A.F.L.-C.I.O., says it is committed to strengthening and broadening its ranks. “Every person who works at the A.F.L.-C.I.O. and every dollar we spend is dedicated to building the labor movement and giving a voice to working people,” said John Weber, its press secretary.
But most unions are reluctant to invest heavily in activities like Ms. Kinema’s efforts at Riot Games, which can invigorate labor activism even if they don’t directly produce new members. “It’s an opportunity being squandered,” said Stewart Acuff, a former organizing director of the A.F.L.-C.I.O. “We’re also squandering our responsibility.”
Of all the cities undergoing labor ferment, Los Angeles — the base of Riot Games, maker of the hit game League of Legends — is arguably at the forefront. The newsroom staff of The Los Angeles Times, a historically anti-labor workplace, unionized last year. In January, the city’s public-school teachers staged a successful six-day strike. In June, grocery workers voted to authorize a strike. Tens of thousands could walk off the job.
“It’s in the air,” said Peter Dreier, an expert on urban policy at Occidental College in Los Angeles. “It’s infected other people.”
Yet even the triumphs have left some workers cold. The teachers’ strike had been gestating since 2014, when a slate of teachers known as Union Power seized on frustration with ballooning class sizes and lagging pay and swept out the union’s leadership.
The new leaders meticulously prepared to strike with escalating protests and rallies, according to a forthcoming book by the organizer Jane McAlevey. But after the district agreed to many of the strike demands — among them raising wages and adding support personnel like nurses and counselors — many teachers grumbled that union officials gave them only hours to review the proposed contract.
“They wanted you to accept the agreement without any kind of debate,” said David Feldman, a high school history teacher who is part of a fledgling campaign to challenge the current leadership. “That’s kind of a pattern of things.”
Gloria Martinez, one of the union’s vice presidents, said the limited time for discussion was a valid concern. “There were a lot of pressures of wanting to get our students back into the school,” she said. “We should have paused for a bit.”
It is not the only union campaign that has left rank-and-file workers seeking more of a say.
One of the country’s biggest groups of Uber drivers, the Los Angeles-based Rideshare Drivers United, has clashed of late with the two-million-member Service Employees International Union over talks that the S.E.I.U. and other unions have held with Uber and its ride-hailing rival Lyft. The talks explored a way to exempt the companies from having to classify drivers as employees covered by minimum-wage laws and workers’ compensation, which a bill in the State Legislature known as A.B. 5 would require. In exchange, a deal could have made it easier for a union to represent the drivers.
At a meeting Wednesday night of the drivers’ group, Nicole Moore, who sits on its organizing committee, complained that the S.E.I.U. was trying to muddy the waters by claiming to back the bill after exploring ways to scale it back without driver input. “Even though S.E.I.U. is supporting A.B. 5 now, we weren’t sure if they were going to jump out from behind the bushes and compromise,” she said.
The S.E.I.U. said it had never sought a deal that would trade away drivers’ rights and that driver input was critical. Linda Valdivia, an Uber driver who is a member of an S.E.I.U.-funded driver group, said, “Everything is under our authority — they ask us and we approve it.”
In other cases, unions have held back until workers indicate that they want to become members.
Matthew D. Loeb, president of the International Alliance of Theatrical Stage Employees, said his union was willing to send in a full-time professional organizer to help workers at a game studio once they decide to affiliate with his union. “We’re prepared to provide all sorts of resources — legal, communications, corporate pressure,” Mr. Loeb said.
The union has held occasional discussions with workers, but has largely deferred to Ms. Kinema and her colleagues at Game Workers Unite.
Ms. Kinema, who trained with the Industrial Workers of the World, a traditionally radical labor group, said that the support from unions like Mr. Loeb’s was real but that the undertaking “needs capital.”
She makes $13 an hour as a quality-assurance tester for a game developer in Orange County and lives in a two-bedroom apartment with three other people. She estimates that she typically spends 60 hours a week attending conferences and training and advising workers, efforts she underwrites with an online fund-raising account that yields nearly $1,000 a month.
After workers at Riot Games attended a Game Workers Unite meeting in Los Angeles last year, she helped them set up a small organizing committee. Several weeks later, Kotaku, a website that covers the industry, published an account of sexual harassment and discrimination at the company, and the article’s impact added momentum to the organizing push.
In the week before the walkout, Ms. Kinema held daily calls with the planners to advise them on tactics, like what literature to circulate and how to manage a crowd of over 100 people.
“Emma was invaluable leading up to the walkout,” said Jocelyn Monahan, one of the Riot employees who helped plan it.
Ms. Kinema’s work is beginning to pay off. As recently as early August, the walkout leaders had not focused on building a formal entity like a union. But Ms. Kinema made the case that just getting workers together to vent without any power to resolve their frustrations “can feel really defeating,” Ms. Monahan said. She and her colleagues want to create a worker-led organization to help solve problems like overwork and burnout, though it will not necessarily be a union.
In principle, an umbrella group like the A.F.L.-C.I.O. might be better positioned than individual unions to fund what Ms. Kinema refers to as the foundational work of training and educating workers. But the federation has substantially cut its organizing budget in recent years, according to documents obtained by the website Splinter.
Ana Avendaño, a former A.F.L.-C.I.O. official, said a partnership that she helped start in 2006 between the federation and so-called worker centers, which assist employees in organizing but aren’t unions, had been de-emphasized. “The idea of growing the labor movement just to build worker power,” said Ms. Avendaño, who left the federation in 2014, “is not something that is in the DNA of the leadership.”
Mr. Weber of the A.F.L.-C.I.O. said that years of declining resources amid attacks on labor had made it harder for the federation to award grants, but that its organizing budget did not reflect all its spending on organizing. He said a fund through which the federation invested in certain partnerships, including some that Ms. Avendaño worked on, had actually increased over the past decade, though the increase comes from outside sources.
Even as overall union membership has declined, some unions have experienced gains, such as those representing teachers. Unite Here, which represents hotel workers among others, has added tens of thousands of members since 2014. Another union, the United Food and Commercial Workers, has organized thousands of cannabis-industry workers.
The need to make larger investments in organizing could be a central theme of the campaign to succeed Richard Trumka, the A.F.L.-C.I.O. president, when his term ends in 2021.
Sara Nelson, the head of the Association of Flight Attendants, who has been mentioned as a potential candidate, said the labor movement should shift some of the tens of millions of dollars it spends on political campaigns toward helping workers build unions, even if those investments take years to pay off.
“Polls continue to show increased interest in being in a union,” Ms. Nelson said. “If you were a business that saw those numbers of people who wanted to have access to what you have, and you were only operating at about 10 to 15 percent of the interest, you would do everything you can to get your product or service in the hands of people who want it.”