In 2016, her breakout role came from Kelly Reichardt's Certain Women playing Jamie, a lonely ranch hand, for which she won the Los Angeles Film Critics Association Award for Best Supporting Actress and Boston Society of Film Critics Award for Best Supporting Actress. She also received nominations for the Independent Spirit Award for Best Supporting Female and Gotham Award for Breakthrough Actress.
Gladstone was born and raised in Browning, Montana. She is of Blackfeet and Nez Perce heritage. Her "great, great grandfather, on her mother’s side, was first cousin to william Gladstone, the British prime minister"; "on her father’s side, her great, great grandfather was Red Crow – a treaty chief". She graduated from the University of Montana with a B.F.A in Acting. As a child she performed with the Stone Soup Theatre Company in Seattle. She has also been a member of Living Voices, a touring theatre troupe. Gladstone starting acting as an extra when she was a teenager. She landed her first speaking part in Jimmy P: Psychotherapy of a Plains Indian, alongside Misty Upham.
