A Tree is Nice is a children's picture book written by American writer Janice May Udry and illustrated by American artist Marc Simont. It was published by Harper and Brothers in 1956, and won the Caldecott Medal in 1957. In a retrospective essay about the Caldecott Medal-winning books from 1956 to 1965, Norma R. Fryatt wrote, "The book becomes one of the most convincing sermons on conservation yet done for young children."