Pearce was born in New York City, the only child of Margaret Clark and Robert E. Pearce. Her father was a foreign banking specialist, and her family moved to Europe when she was 18 months old. They lived in Brussels, Antwerp, Rome, and Paris. At age nine, she fell off a swing after losing her grip and landed on her chin. This left her with an undeveloped chin. She returned to the United States as a teenager, and boarded at the Masters School in Dobbs Ferry, New York. She graduated from Sarah Lawrence College in 1940, with a degree in drama.