Born into a Quaker family active in the printing industry in Philadelphia, Milhous is also known for her graphic designs for the Works Progress Administration (WPA).

[4] From 1935 to 1940 Milhous was a supervisor for the Philadelphia Federal Art Project (FAP), a branch of the Works Progress Administration.

[5] Alice Dalgliesh, head of the Children's Book division of Charles Scribner's & Sons, saw Milhous' posters during an exhibition in an FAP gallery, and hired her as a staff designer.

[7] On Patrick and the Golden Slippers, about Philadelphia's Mummers' Parade, the same magazine wrote "This is a picture book of enduring value to young Americans.

"[8] In her Caldecott Medal-winning The Egg Tree, "Her use of bright tempera paints brought to life the bold borders and vibrant pages of the book.