Known best for her Max and Ruby series of children's books, this New York-born illustrator and author also wrote the Voyage to the Bunny Planet books, as well as a historical fiction work titled Red Moon at Sharpsburg.
She illustrated her first children's book, author Ellen Conford's Impossible, Possum, in the early 1970s. Her early solo-written children's books include Unfortunately Harriet and Noisy Nora.
In her Yoko children's books, which focus on the trials and tribulations of a Japanese cat, she addresses the theme of racism.
She grew up in New York and New Jersey. In 1963, she married an architect named Thomas Moore Wells.
She created a series of illustrations of musical theater songs by composer Richard Rodgers and lyricist Oscar Hammerstein II.