There has of late been a call among language practitioners for the sophisticated new markup language XML to be used in Web-based tools for language learning (Mills, 1999; Riley, 2001; Godwin-Jones, 2000). This paper describes just such an application: the development of an interactive electronic resource book of learning tasks for English Language Teaching (ELT). The electronic resource book incorporates an authenticity-centred approach to language learning materials design, viz language learning based on authentic texts complemented by authentic tasks. The paper covers a general introduction to XML, describes the pedagogical model (i.e. the authenticity-centred approach) that it was used to realise, and describes the development of the XML-based system operating the electronic resource book. Among the conclusions of this paper are that this trial application reveals XML to be ideally suited to the realisation of such pedagogical models and that its greatly enhanced information management and linking potential promises an exciting future in the field of language teaching by providing the possibility for pedagogy-led technology rather than technology-led pedagogy.