Cassedy was born January 29, 1930, in Brooklyn, New York.[1] She graduated from Brooklyn College, and worked as a primary and secondary school teacher.[2]
Cassedy is known for her young adult novels.[1][2][3] Her three novels Behind the Attic Wall, M.E. and Morton, and Lucie Babbidge's House feature preadolescent girls as protagonists, who use fantasy and play to improve their circumstances.[2][4]
Besides her young adult novels, Cassedy wrote two volumes of poetry. She translated collections of poems from India and from Japan. Based on her teaching experience, she wrote a guide to creative writing In Your Own Words: a Beginner's Guide to Writing.[2]
Cassedy died April 6, 1989, in Manhasset, NY.[1] Her collected papers are held by the University of Minnesota.[5]
Red Dragonfly on my Shoulder, with Kunihiro Suetake (HarperCollins, 1992). Illustrated by Molly Bang. ISBN0060226242[14] Revised and retitled from Birds, Frogs, and Moonlight by the same authors (Doubleday, 1967). Illustrated by Vo-Dinh.[2]