Daniel Dae Kim promoting “Hawaii Five-O” in 2013. (George Pimentel/Getty Images)

Questions of diversity and equality have been hotly debated in Hollywood in recent years. And over the last week, three actors drew lines in the sand. First, Michelle Rodriguez, who stars in the long-running “Fast and Furious” franchise, said she was contemplating leaving the series if the roles for women didn’t improve in subsequent installments. And over the weekend, actors Daniel Dae Kim and Grace Park quit the reboot of “Hawaii Five-O” amid reports that they had been unable to secure contracts that would have closed a pay gap of between 10 and 15 percent that separated them from their white, male co-stars.

This sort of militancy is welcome and, given Hollywood’s glaring inequities, long-overdue. It also provides a nice opportunity for all the stars who have made progressive politics part of their brand to prove just how committed they are to those ideas.

No one should discount the risks that Kim, Park and Rodriguez are taking. Hollywood is a project-based industry, so a long-running television show or movie franchise provides unusual stability. Leaving one means walking away from a steady paycheck. And quitting a TV or movie series over pay equity or gender issues in writing means these actors may face being labeled difficult or mercurial at precisely the moment when they need to audition for new jobs and negotiate new contracts.

That said, while the entertainment industry may be precarious, the people who work in it at the highest levels are in a better position to stick to their principles than workers in many other fields. TV and movie stars are highly compensated, so if they manage their money carefully, they don’t have to choose between fighting for fairness and paying their bills. Unlike much of the rest of the American workforce, writers, actors and directors are protected by unions. And actors have agents and managers who can help get them back to work.

Indeed, just because Kim and Park’s negotiations broke down doesn’t mean that standing firm is a bad move.

Emmy Rossum negotiated pay equity with her “Shameless” co-star, William H. Macy. Macy backed her publicly. Robin Wright tried to demand a per-episode salary equal to Kevin Spacey’s on “House of Cards” but was stymied by the fact that Spacey has a producer credit that increases his total compensation; she won a new title and the opportunity to direct some episodes of the Netflix series.

Both these examples offer some lessons for other actors. Being the co-lead on a series, rather than part of an ensemble, helps. So does having a back-end role that entitles you to a higher salary or a percentage of the back end. And solidarity from men matters. Just as Macy went public with his support for Rossum’s new contract, “Fast and Furious” franchise star Vin Diesel posted a video he and Rodriguez made together in which she made it clear that her criticisms weren’t directed at him, and he was publicly affectionate to her at a time when he might have distanced himself from her and her comments.

Actors should keep standing up and standing firm. And if their co-stars really care about equality, they should stand with them.

Male actors should demand pay parity and well-developed roles for their female co-stars on the grounds that a movie or show will always be better if all the characters are well-rounded. Stars such as Jennifer Lawrence and Meryl Streep, both of whom have talked publicly about compensation issues in their industry, should use their clout to advocate not only for themselves, but for their co-stars of color.

After all, if your contract is going to include everything from how your name has to appear on screen in a credits sequence to whether or not you get to approve non-photographic images of yourself that are part of a marketing campaign, why not use some of your clout to improve conditions for everyone on a project? Having a nice trailer is wonderful. But making sure your co-stars don’t have to be preoccupied with ongoing inequities is another route to a set that’s happy for everyone.

If Hollywood’s big names make these demands all at once, then no one has to be singled out as difficult and no one has to wait in line for another group of actors to achieve pay equity. The coming months and years will be a test of whether stars step up to support people such as Kim, Park and Rodriguez and the larger principles at stake, or whether they are interested in salary parity for themselves and gender or racial equality only when it doesn’t cost them anything.