Frank Capra’s 1946 Christmas movie It’s a Wonderful Life is regularly listed as one of the greatest holiday films of all time, and among James Stewart fans is often cited as one of the best movies he ever made.

Besides its leading man, It’s a Wonderful Life also starred Lionel Barrymore, Henry Travers, and future Oscar winner Donna Reed as Stewart’s on-screen wife, Mary Bailey. Reed almost didn’t land the part thanks to some stiff competition from Jean Arthur, who had already proved her on-screen chemistry with Stewart as his co-star in the hugely successful You Can’t Take It With You (1938) and Mr. Smith Goes to Washington (1939).

Jean was Capra’s first choice for the role of Mary, but a prior commitment to Broadway meant that she was unavailable to shoot, and when a string of other Hollywood leading ladies—including Olivia de Havilland and Ginger Rogers—turned the part down, it was offered to the relatively unknown Donna Reed instead.

Reed was by no means a newcomer by that time, having already been featured in nearly two dozen smaller parts and productions by the mid-1940s, but It’s a Wonderful Life was to be her first starring role. Undaunted, she and Stewart quickly bonded over their childhoods:

Both had grown up in small towns, Stewart as the son of a hardware shop owner in Indiana, Pennsylvania, and Reed as a farmer’s daughter from Denison, Iowa. Their humble beginnings reportedly amazed their co-star Lionel Barrymore, who found it hard to believe that the glamorous and eminently professional Reed could have come from such unassuming stock—and promptly struck a bet with Reed that she couldn’t milk a cow.

As luck would have it, there was a cow on set that day, and Reed jumped at the chance to show her hidden talents. “It was the easiest $50 I ever made,” she later commented.