No other work prior to Chaucer's is known to have set a collection of tales within the framework of pilgrims on a pilgrimage. It is obvious, however, that Chaucer borrowed portions, sometimes very large portions, of his stories from earlier stories, and that his work was influenced by the general state of the literary world in which he lived. Storytelling was the main entertainment in England at the time, and storytelling contests had been around for hundreds of years. In 14th-century England the English Pui was a group with an appointed leader who would judge the songs of the group. The winner received a crown and, as with the winner of the Canterbury Tales, a free dinner. It was common for pilgrims on a pilgrimage to have a chosen "master of ceremonies" to guide them and organise the journey. Harold Bloom suggests that the structure is mostly original, but inspired by the "pilgrim" figures of Dante and Virgil in The Divine Comedy.
The Decameron by Giovanni Boccaccio contains more parallels to the Canterbury Tales than any other work. Like the Tales, it features a number of narrators who tell stories along a journey they have undertaken (to flee from the Black Plague). It ends with an apology by Boccaccio, much like Chaucer's Retraction to the Tales. A quarter of the tales in Canterbury Tales parallel a tale in the Decameron, although most of them have closer parallels in other stories. Some scholars thus find it unlikely that Chaucer had a copy of the work on hand, surmising instead that he must have merely read the Decameron at some point. Each of the tales has its own set of sources which have been suggested by scholars, but a few sources are used frequently over several tales. These include poetry by Ovid, the Bible in one of the many vulgate versions it was available in at the time (the exact one is difficult to determine), and the works of Petrarch and Dante. Chaucer was the first author to utilise the work of these last two, both Italians. Boethius' Consolation of Philosophy appears in several tales, as do the works of John Gower, a known friend to Chaucer. A full list is impossible to outline in little space, but Chaucer also, lastly, seems to have borrowed from numerous religious encyclopaedias and liturgical writings, such as John Bromyard's Summa praedicantium, a preacher's handbook, and Jerome's Adversus Jovinianum. Many scholars say there is a good possibility Chaucer met Petrarch or Boccaccio.