Malory's use of his sources, both his major and his minor, varies from tale to tale. In his first, second, fifth, and sixth tales, he follows a single major source fairly closely, and he may have done so as well with the lost source of the fourth tale. In his third, seventh, and eighth tales, Malory combines two or more major sources to create new narrative units. The common feature that characterizes Malory's handling of his major sources is that each one supplies the significant elements of plot for its equivalent tale of the Morte Darthur.

All of Malory's major sources told stories that fit an overall cyclic scheme resembling that of the Vulgate Cycle and Post-Vulgate Cycle. The Post-Vulgate Suite du Merlin provided a set of adventures alternative to those in its Vulgate counterpart, and the alliterative Morte Arthure tells a version of the Roman War story, which also appears near the end of the Vulgate Suite du Merlin. The Prose Lancelot, of course, is part of the Vulgate Cycle, and Malory's use of it was probably influenced by the similar use of the Lancelot by the Post-Vulgate Cycle. The Prose Tristan was designed to be a counterpart to the Lancelot. The Queste de la Saint Graal and the Mort de la roi Artu are the final branches of the Vulgate, and the stanzaic Le Morte Arthur tells much the same story as the Mort Artu.