For reasons unknown, Chaucer left The Canterbury Tales incomplete and without final revision. The work survives in ten fragments, labeled with Roman numerals in this edition (the alphabetical designations added in parentheses are those of the Chaucer Society, adopted by Skeat in his edition). These fragments are editorial units determined by the existence of internal signs of linkage -- bits of conversation or narrative that explicitly refer to a tale just told or to one that immediately follows. There are no explicit connections between the fragments (save for IX-X and, in the tradition of the Ellesmere manuscript, IV-V) and, consequently, no explicit indication of the order in which Chaucer intended the fragments to be read. (Indeed, there is no explicit indication that he had made a final decision in this matter.) Consequently, modern editions differ in the order in which the tales are presented. Skeat's edition has them in the order followed by the Chaucer Society, with the "shift" proposed by Henry Bradshaw, whereby Fragment VII (B2) is printed following Fragment II (B), and with Fragment VI following next, so that the complete arrangement is as follows: I (A), II (B), VII (B*), VI (C), III (D), IV (E), V (F), VIII (G), IX (H), X (I). Baugh and Pratt follow this order except for the position of Fragment VI, which they print following Fragment V. Donaldson and Fisher print the tales in the order followed here. Robinson chose that order even though he believed it probable that the "Bradshaw shift" was indeed what Chaucer intended; nevertheless, he wrote, "in the present edition the inconsistent arrangement of the best manuscripts" (by which he meant the Ellesmere and related manuscripts) "is followed and no attempt is made to correct discrepancies left standing by the author."
(Quoted from The Canterbury Tales, ed. L. D. Benson, Houghton Miflin Co., Boston, 2000, p. 3; cf. The Riverside Chaucer, p. 5: quoted with permission of the publisher.)
Obviously the matter of the proper order in which one should read the Tales (or whether any order is valid) is a subject if considerable critical disagreement. However, beginning students will not go far wrong if they read the tales in the order in which they appear on this Chaucer page and in which they are printed in the Riverside editions. This order is well attested by the manuscripts. (Advanced students may wish to consult Larry D. Benson, "The Order of 'The Canterbury Tales'," Studies in the Age of Chaucer 3 (1981), 77-120, and, for a contrary view Derek Pearsall, The "Canterbury Tales," George Allen and Unwin, London, Boston, Sydney, 1985.)