The actress have teamed up with Cher, Ron Howard, Oliver Stone, Sergio Mendes and others in supporting the International Labour Organization’s fight to end slave labor around the world.

For most Americans, slavery is a relic of the Antebellum South, something that ended forever with Lincoln’s Emancipation Proclamation.

The truth is that an estimated 21 million people around the world—most of them women and children—toil as forced labor or work in conditions so oppressive that they can be called “slave-like.” Tragically, one out of every four contemporary slaves is a child. The situation has struck an increasingly resonant chord in Hollywood’s conscience, which is why a new group of top-drawer celebrities has signed on to support the International Labour Organization’s global “End Slavery Now!” campaign.

Cher, Jada Pinkett Smith, Mila Kunis, Ron Howard, Oliver Stone and Sergio Mendes are among those who’ve recently joined the effort. Already on board are Chaka Khan, Dan Kennedy, Danny Glover, Hans Zimmer, Maria Bello and Paul Haggis. Pinkett Smith this week released a video appeal for the ILO, a subsidiary of the United Nations.