She is the sweetheart and later wife of protagonist George Bailey (played by James Stewart as an adult and Bobby Anderson as a child).

She is loosely based on Mary Pratt, a character in Philip Van Doren Stern's 1943 short story The Greatest Gift.

[6][7] Her first appearance is when she is a little girl in a pharmacy ordering malts with her schoolmate Violet Bick and being waited on by a young George working the soda fountain.

[10][9] That evening, George's friends Bert the cop and the cab driver Ernie escort him to his "new" home: the Old Granville house, a derelict mansion Mary had wished for years before.

[8] Mary becomes a volunteer for the war effort, such as running the local branch of the USO, while raising their four children (Pete, Janie, Tommy, and Zuzu).

"[25] Before Reed got the role, it was offered to Olivia de Havilland, Ginger Rogers, Jean Arthur, and Ann Dvorak.

[26] In the "wishing" scene outside the old Granville house, Capra was surprised to see Reed accurately throw a stone to break a window, a skill she acquired playing baseball with her brothers on their Iowa farm.