Brown was born in New York City on October 15, 1933. She attended Cooper Union and the Parsons School of Design and received a Bachelor of Arts degree in art history and English from New York University in 1956. Brown learned the technical aspects of book design and offset printing while working for a printer doing paste-ups and book jackets from 1958 to 1960. Since 1959 she has been a free-lance illustrator.

"The working out of art on any level takes so much time; not just the doing of it, but the time spent thinking about it, and being concerned with the work of others. I try to read as much as I can and look at pictures of all kinds. I particularly enjoy 19th century fiction, and I make a point of reading poetry every day. I also go to the museums so that I might keep in mind what is truly imaginative, rare and great, and continually affirm to myself what is most important even when I am least sure of my own efforts."

Her first book, Marjorie Paradis' Mr. De Luca's Horse, was published in 1962. Since then Brown has illustrated more than forty books and has written and illustrated four of her own, as well as contributed to anthologies, periodicals, and the New York Times. Among the many famous children's authors whose works she has illustrated are Padraic Colum, Margaret Hodges, Elizabeth Coatsworth, Noel Streatfeild, and Andre Norton.