At the time when it was fashionable to study in Europe, Pyle had a strong conviction that students should seek their training and inspiration in America. In his later years, Pyle devoted most of his time to teaching such outstanding illustrators as Maxfield Parrish, N. C. Wyeth and Harvey Dunn whom he inspired as much by his idealism as by the high standards he set for picture making. Pyle, who made no charge for his teaching, built a set of studios for the students to work in. After Pyle's death, his students collected many of his original paintings as a nucleus for the collection of his work in the Delaware Art Museum.
His 1883 classic "The Merry Adventures of Robin Hood" remains in print to this day, and his other books, frequently with medieval European settings, include a four-volume set on King Arthur that cemented his reputation.
He wrote an original novel, "Otto of the Silver Hand", in 1888. He also illustrated historical and adventure stories for periodicals such as Harper's Weekly and St. Nicholas Magazine. His novel "Men of Iron" was made into a movie in 1954 ("The Black Shield of Falworth").
Pyle traveled to Florence, Italy to study mural painting in 1910, and died there in 1911 of sudden kidney infection.
Pyle was widely respected during his life and continues to be highly regarded by illustrators and fine artists. His contemporary Vincent van Gogh spoke of Pyle in a letter to his brother, saying that Pyle's work "...struck me dumb with admiration".