Running down a list of thank-you's heard often over the past few months -- her famous siblings, director Richard Linklater and costar Ethan Hawke -- she surprised at the end of her speech by invoking the journey of her single-mom character in "Boyhood."
"To every woman who gave birth, to every citizen who has paid taxes ... this is our time to have wage equality and equal rights for women," Arquette said.
The line elicited strong reactions and applause from the crowd, with Meryl Streep and Jennifer Lopez rising from their chairs with applause. Arquette also name-checked her charitable foundation GiveLove.org, founded with Rosetta Getty, which helps displaced families.
Arquette claimed the trophy over Emma Stone of "Birdman," Streep in "Into The Woods," Keira Knightley in "The Imitation Game" and Laura Dern in "Wild."
Watch Arquette's speech here.
The text of her speech, courtesy of the Academy:
Okay, Jesus. Thank you to the Academy, to my beautiful, powerful nominees. To IFC, Jonathan Sehring, John Sloss, Cathleen Sutherland, Molly Madden, David DeCamillo, our whole cast and our crew. My "Boyhood" family, who I love and admire. Our brilliant director Richard Linklater. The impeccable Ethan Hawke. My lovelies, Ellar Coltrane, Lorelei Linklater. Thomas and Paul, thank you for giving me my beautiful children. Enzo and Harlow, you’re the deepest people that I know. My friends who all work so hard to make this world a better place. To my parents, Rosanna, Richmond, Alexis and David. To my favorite painter in the world, Eric White, for the inspiration of living with a genius. To my heroes, volunteers and experts who have helped me bring ecological sanitation to the developing world with GiveLove.org. To every woman who gave birth, to every taxpayer and citizen of this nation, we have fought for everybody else’s equal rights. It’s our time to have wage equality once and for all and equal rights for women in the United States of America.