The Helen Day Memorial Library and Art Center in Stowe, Vermont, is now named for her.
In the 1940s, Montanari and her partner, Dr. Marguerite Lichtenthaeler (1887–1974), ran an "Aryans-only" inn, the Attic & Barn, in Stowe.
For nearly two decades, brochures offering lodging options for visitors to Stowe included those which excluded people of Jewish faith.
[7] Years later, there was a successful campaign to raise the remainder of the money that was needed for the Stowe Free Library and the Helen Day Art Center.
[8][9] Day married Carlo Montanari, a Harvard graduate and member of the Italian Army,[2] on April 20, 1904, the ceremony taking place in Eliot Congregational Church in Eliot, Maine,[1] although another source states it took place in Newton, Massachusetts.