Armstrong W. Sperry was born on November 7, 1897, in New Haven, Connecticut. As a boy, he was captivated by his great-grandfather's stories about the South Seas. With America's entry into World War I in 1917, he enlisted in the U.S. Navy. He attended the Yale School of Fine Arts in 1918, the Art Students League in New York from 1919 to 1921, and spent the following year studying art in Paris.

A book by Frederick O'Brien, White Shadows in the South Seas, reawakened Sperry's childhood dreams and after two years working at an advertising agency in New York, he joined the Kaimiloa expedition as an assistant ethnologist for the Bishop Museum of Honolulu. Sperry sailed among the islands of the South Pacific for two years, studying the languages, legends, and ancient chants of the Polynesians. When he returned to the United States he began working as an illustrator in New York. Eight years later, the impulse came to him to write and illustrate a book for children, and his instinctive choice of subject was Polynesian. After that first simple book, One Day with Manu (1932), he wrote about the sea again and again. In 1940 he published Call It Courage, which is considered his best book in this genre.

Sperry also traveled extensively across Europe and America in search of ideas, and once followed the Sante Fe Trail in his car while researching his book Wagons Westward. When not traveling, Sperry divided his time between his New Hampshire home and the farm in Vermont where the family spent its summers. He died April 28, 1976, in Hanover, New Hampshire.

During his writing career, Sperry won a number of literary awards, including the 1941 Newbery Medal for Call It Courage. In 1944 he won the New York Herald Tribune Children's Spring Book Festival Award for Storm Canvas and in 1949 the Boys Clubs of America awarded him its Junior Book Award for The Rain Forest.