What was the first book printed in English?

The first book printed in English is The Recuyell of the Historyes of Troye, a prose romance by Raoul Lefevre, printed by William Caxton in 1474 in Bruges, Belgium.

Caxton himself translated it from the French.

Caxton also printed the first dated book printed in English, Dictes and Sayenges of the Phylosophers, published on November 18, 1477.