-- A bunch of female stars disappeared on social media Sunday.
Celebrities quickly followed suit.
"We're Not There ... Yet," Diaz wrote on her Instagram account. "Inequality exists at work / at home / at the doctor's office / at school - and yet these issues do not get the attention they deserve. It's almost like we're NOT THERE at all."
On her Instagram account, Nyong'o wrote, "For International Women’s Day, I am taking a stand for gender equality and I'm joining others to be #NotThere."
Poehler, Diaz and other female celebrities explained the effort in a video on the campaign's website.
Other stars marked International Women's Day with their own messages.
"Girls" star Allison Williams gave a fist bump to her co-stars on Instagram.
"So thankful to have so many strong women in my life. We're not there yet, but we're getting there. Going to be spending it with my GIRLS family at PaleyFest," she wrote.