Hundreds of employees at Google and its parent, Alphabet (GOOGL), have launched a union.

This is a rare step for the tech industry that also represents the biggest and most organized challenge yet to Google’s executive leadership.

On Monday morning, the Alphabet Workers’ Union announced that it will be run by employees and open both to full-time workers and contractors at Google.

“This is historic,” Dylan Baker said, a Google software engineer. “The first union at a major tech company by and for all tech workers. We will elect representatives, we will make decisions democratically, we will pay dues, and we will hire skilled organizers to ensure all workers at Google know they can work with us if they actually want to see their company reflect their values.”

According to a New York Times op-ed, the group published Monday morning that the initiative launched with more than 200 members.

Around 226 of the group’s members have signed union cards with the Communications Workers of America (CWA), one of the nation’s largest labor unions.

Andrew Gainer-Dewar, a Google software engineer who helped lead the effort said that the work to build the union began in secretly over a year ago.

“You have to organize one-to-one, in sort of a very cloak-and-dagger way,” Gainer-Dewar told CNN Business, “meeting with people, broaching the subject carefully, being really thoughtful about who we tell what, when, and really only reaching out based on their personal relationships, the people that we see being publicly upset about issues.”

He added that while the pandemic made it more challenging to hold those meetings face-to-face, the shift to remote work made it easier to organize.

“Video calls are a fantastic one-to-one mechanism,” he added. “And the fact that we’re not having it in the office takes us out from under the all-seeing eye of a company like Google.”

Unions can be certified when a majority of workplace votes to support one in an election held by the National Labor Relations Board. Alternatively, a union can be voluntarily recognized by an employer if enough workers indicate they would like the union to negotiate on their behalf, according to the NLRB.

Beth Allen, communications director at CWA said that the Google workers have opted for a third approach that, at least for now, does not anticipate formal recognition. The reason is that traditional collective bargaining agreements “almost always exclude contractors,” Allen said, which was a nonstarter for many of the Google organizers.

Allen added that Google workers could also theoretically mount a strike, though that would be a challenge and there are no current plans to do so.

As a response to the union, the company pledged to engage with workers.

“We’ve always worked hard to create a supportive and rewarding workplace for our workforce,” said Kara Silverstein, Google’s director of people operations, told CNN Business. “Of course our employees have protected labor rights that we support. But as we’ve always done, we’ll continue engaging directly with all our employees.”