— -- Lady Gaga was joined by victims of sexual assault for a stirring performance of her Oscar-nominated song "Til It Happens to You," from the documentary "The Hunting Ground."
The song was introduced by Vice President Joe Biden, who implored the audience to take a pledge at ItsOnUs.org to "change the culture, so no abused woman or man should ever have to ask themselves what did I do."
Gaga then appeared alone on stage, seated behind a white piano.
Singing powerfully the words, "til it happens to you, you don't know how it feels," she was joined by a dozens of abuse survivors. After standing in the shadows, they joined her on stage at the song's climax. On each of their forearms was written different words, including "unbreakable" and "survivor." Together they joined hands with the singer as the audience rose to their feet, clearly moved by Gaga's performance.
Nominee Rachel McAdams wiped away tears, as Gaga's co-writer, eight-time nominee Diane Warren, looked blown away.
Earlier on the red carpet, Gaga told ABC News' Robin Roberts why the song was "such an important song to me."
"One in five women will be raped before the time they finish college," she said. "It's something that is deeply connected to my heart. I myself am a survivor."
The Grammy-winning singer told Roberts that she was "very grateful to the Academy for giving us this world stage to reward survivors for being brave and coming forward."
Even though Gaga lost the Oscar to Sam Smith, the singer is on fire this year.
Last month, she won her first Golden Globe for acting for her starring role in "American Horror Story: Hotel." Earlier this month, she knocked it out of the park with her performance of the National Anthem at the Super Bowl and her tribute to the late David Bowie at the Grammys.