Chastain was born and raised around Sonoma, California. She is one of five children. Her mother is a vegan chef, and her father is a firefighter. She grew up as Jessica Howard and later took her mother's maiden name as her stage name.
In the past few years Chastain's career has taken off. Chastain has won many awards for her roles in Take Shelter, Coriolanus, The Debt, Tree of Life, The Help and Zero Dark Thirty.
