This thesis is an examination of the effects of translation into French and of adaptation for the stage, in English, on the dialogue of Philip Pullman’s novel Northern Lights (published in North America as The Golden Compass). The study focuses on the speech of Lyra, the novel’s protagonist, in terms of both its linguistic qualities and the functions it supports within the novel and the trilogy of which it forms part, His Dark Materials. The study aims to identify the ways in which not just the linguistic surface of fictional speech is affected by translation and adaptation but also the degree to which the roles played by the dialogue in the source text are reflected or transformed in the different versions. The unusual research design, involving a comparison of the effects of interlingual translation and intermedial adaptation on the same text, consists of two main elements. In the first quantitative section, the relative incidence of three variables is measured for the purposes of identifying how features of spoken style and non-standard variation are treated. This analysis is followed by a detailed qualitative evaluation of a small number of dialogue passages that exemplify the key linguistic features and likely textual functions of Lyra’s speech in the novel. The passages concerned are compared with equivalent stretches of dialogue in the French translation and the theatrical script. The study finds evidence to suggest that Pullman uses dialogue in support of characterisation, plot, and also ideological and intertextual concerns. All of these aspects are affected, in subtle but significant ways, by the different decisions made by the translator and the dramatist in respect of Lyra’s speech. The study also finds that aspects of both user-related and situation-related variation in fictional speech may be worthy of further research.