Darling was born in
Stamford, Connecticut, and would live in Connecticut for most of his life. He attended the
Grand Central School of Art in New York City. Also in 1946, Darling was hired by
William Morrow and Company to illustrate
Roderick Haig-Brown's book
A River Never Sleeps. Subsequently, he began illustrating, and then writing, children's books, mostly for Morrow. He was assigned to
Beverly Cleary's first book,
Henry Huggins, in 1950, which began his best-known association; he would illustrate most of Cleary's books until his death. The character of Huggins was called a "modern Tom Sawyer" in the 1950s. He wrote his first book,
Greenhead, in 1954. He would later write: "I started to write my own books because it seemed to me that there was seldom enough cooperation between author and illustrator. The best way to get this cooperation was to become the author myself." Darling wrote and illustrated ''
The Gull's Way'', a book about
American herring gulls on an island in
Maine, which was published in 1965. To research it, he had camped alone on the uninhabited island for six weeks, observing and photographing the gulls. The book won the
John Burroughs Medal in 1966. His final collaboration with Lois was
A Place in the Sun: Ecology and the Living World, published in 1968. Darling died of cancer in 1970 with Cleary dedicating her book
Runaway Ralph to him. ==Environmental activism==