The Middle English alliterative verse William of Palerne (sometimes known by its early title, William and the Werewolf) is a fourteenth-century translation of the Old French Guillaume de Palerne. Both the English and French narratives tell the interlinked stories of William, a prince of Palerne, who escapes from the plotting of his murderous uncle with the help of a benevolent werewolf, and of Alphons, the Spanish prince who is forced into lycanthropic form by his necromantic stepmother. There are, however, some striking differences between the insular and continental versions of the story (which also appears in later English and French prose versions, as well as an Irish adaptation), and this essay will go some way to examining what we might note as a particular thematic concern of the Middle English verse narrative. In his 1985 edition of the poem, G. H. V. Bunt argues that the English poet ‘has written a very different poem from his French source’, and I would like to offer some exploration of themes of sexual and gender performance which I believe characterize the English poem particularly. The first half of the English William reveals a preoccupation with disguise and role-playing, which is not found in the French source text. This is especially apparent in the presentation of the relationship between William and Melior, the emperor of Rome's daughter, and in their meeting, attraction and elopement.