An imprint of HarperCollins.

From http://www.harpercollins.com/hc/aboutus/imprints/willow.asp

Since its inception in 1974, Greenwillow Books has been publishing books for children of every age. We hope that at the heart of each book there is honesty, emotion and depth--conveyed by an author or an artist who has something that is worth saying to children and who says it in a way that is worth reading.

From the back flap of The Homeward Bounders:
GREENWILLOW BOOKS
105 Madison Avenue
New York, N.Y. 10016