The actresses announced on Twitter they will be joining the Women's March demonstration to campaign for equality and women's rights on 21 January (17), the day after Donald Trump is sworn in as U.S. President on 20 January (17).

The Washington, D.C. march is expected to be the largest of more than 200 similar marches being planned in other U.S. states and more than 20 other countries, including the U.K., on the same day.

Julianne tweeted a picture of the march's poster and wrote in the caption, "On Jan 21st, I'll be at the @womensmarch fighting for equality, because women's rights are human rights. #WhyIMarch."

Jessica shared the post and added, "I'll see you there! (love heart emoji) @_juliannemoore," and the Boogie Nights actress replied, "Yay," followed by blowing a kiss, thumbs up, and rainbow emojis.

They aren't the only celebrities supporting the cause. Chat show host Chelsea Handler has announced she will lead the march and host a rally in Park City, Utah, where the Sundance Film Festival will be taking place.

"If there's anything I learned in the last year, it's that we need to be louder and stronger than ever about what we believe in, so I joined some incredible women from around the country to bring our voices together in the streets of Park City," she said in a statement. "The Women's March on Main (Street) will be an opportunity for the creative community and those in Utah to stand beside those in D.C."

Documentary maker Michael Moore and Fresh Off the Boat actress Constance Wu have also announced their participation in the D.C. march on social media.