The major edition of the three versions of Piers Plowman which the Athlone Press is in the process of publishing and of which Professor Kane is the general editor was not planned to include discussion of the authorship of the poem. The editors were agreed at the outset in believing that no real case for multiple authorship had been established in the course of the debate initiated by J. M. Manley in 1906, and they felt that a majority of Middle English scholars would support this view. They were satisfied that the hypothesis of single authorship was the best hypothesis to account for all aspects of the relation between the versions of the poem. However, the recent appearance of a book comparing the A and B versions in the belief that they were not written by the same man led Professor Kane to make a survey of the arguments advanced in support of multiple authorship and to examine again the evidence for single authorship. This re-assessment was originally undertaken without specific reference to the new edition of the three versions, but the unexpectedly positive character of Professor Kane's findings has a bearing on the edition by materially reducing the hypothetical element in the editorial position. The results of the inquiry are therefore published as a supplementary volume to the text edition and in an identical format.