The Quest for El Cid is a work of popular history and biography by Richard Fletcher, an academic historian, published in 1989. The Historia Roderici is an anonymous document written in Latin, probably about two decades after the death of Rodrigo Díaz in 1099. The differences between the two works are much as one would expect from these brief descriptions. Fletcher's account attempts to be even-handed and draws on many sources. The author of the Historia refers to no other works except the Bible, and presents Rodrigo uncritically as a hero. The coverage is uneven, and relatively little is said about Rodrigo's role in the Kingdom of Castile.

As El Cid, Rodrigo Díaz, is often depicted as the quintessential Spanish national hero, a key figure in the Reconquista. The Historia Roderici is too early a source to take exactly this line, since the idea of "Spain" did not exist when it was written. Nonetheless, it does depict a Christian European hero fighting against the Moors. Fletcher's portrait is quite different. It presents Rodrigo as first a mercenary, then a warlord. In the former capacity, he fought for both Christians and Muslims, and does not seem to have made much of a distinction between them. The sobriquet El Cid, is actually a corruption of the Arabic sayyid, meaning "master." Fletcher does not see Rodrigo as a particularly negative figure by the standards of his time, but he makes it clear that he fought for himself and his men, rather than for Spain or Christendom.