Employees at Hearst Magazines announced on Monday their plans to form a union, setting off a massive effort across 24 media brands that encompass print and digital staffers in editorial, video, photo, design and social.
Participating publications include Cosmopolitan, Delish, Men's Health, Oprah Winfrey's "O" magazine and Esquire.
A "strong majority" of the 500-member staff signed union cards with the Writers Guild of America, East, according to a press release. That scale makes it one of the largest editorial unions in the media industry.
Hearst joins a slew of other media companies that have unionized in recent years. Condé Nast has had individual brands unionize, including The New Yorker. Digital outlets that have unionized include BuzzFeed News, Vox Media and Vice Media. The digital news employees at NBC News announced their intention to unionize with NewsGuild last month.
"Hearst's union drive comes as the media industry continues to consolidate, as companies become platform-agnostic and offer content on paper, over the airwaves, and online. Unionizing, winning recognition, bargaining contracts, this is how people who craft content ensure that their voices are heard and their workplace needs are met," Lowell Peterson, executive director of Writers Guild of America, East, said in a statement.
Hearst's effort is unique in that it's a joint initiative in print and digital and across publications. Staffers started organizing about a year ago and built an organizing committee of about 55 people, said Olivia Fleming, digital features director at Harper's Bazaar and one of the union organizers.
"It's been really, really nice to join forces in that way and to connect with other people at the company in a really meaningful way," Fleming told CNN Business. "We're building great relationships with our coworkers through this."
The union hopes to improve workplace issues like transparency, diversity in hiring and leadership, fair compensation and clear editorial standards.
"Given how precarious the state of media is today -- every day you see something on Twitter -- we know how profoundly lucky we are at Hearst. But we want to make sure we're safeguarding the future. We want to understand how the company operates, feel like we have some sort of say," Julie Kosin, culture editor at Elle, told CNN Business.
Hearst did not immediately respond to CNN Business' request for comment.