Avi was born in 1937, in the city of New York and raised in Brooklyn. He began his writing career as a playwright, and didn't start writing childrens books until he had kids of his own.
Bill is a graduate of the Ringling School of Art and Design. He has created paintings for magazines, advertisements, and children's books as well as commissioned portraits and landscapes. His children's books have received the Young Hoosier Book Award, the NAPRA (Network of Alternatives for Publishers, Retailers, and Artists) Nautilus Award, and the Lee Bennett Hopkins Poetry Award. He lives with his family in Venice, Florida.