Best known for playing the President's daughter in the television series The West Wing and as Peggy Olson in the television series Mad Men. She won the Primetime Emmy for Outstanding Lead Actress in a Drama Series for her role in Hulu's The Handmaid's Tale.
One of her earliest roles was providing the voice of Holly DeCarlo in the Christmas show Frosty Returns in 1992.
In 2019, she starred in the horror film Us.
She was briefly married to Fred Armisen from 2009-2011.
She played the younger version of Ashley Judd in Love Can Build A Bridge.