Introduction Textbooks play a special role in the context of knowledge construction and communication, as they provide access to specialized knowledge and help readers construct a mental representation of specific disciplinary knowledge. Their nature has been variously investigated by discourse analysts (Halliday & Martin 1993; Swales 1990, 1995; Altienza & van Dijk 2011) and historians of science (Kuhn 1970; Bazerman 1988; Klamer 1990). The key role they play in learning contexts – both in secondary (Bezemer & Kress 2008, 2009) and tertiary education (Myers 1992; Swales 1995; Hyland 1999; Richardson 2004; Biber 2006) – has influenced the way they have been described as a genre, as well as their changing fortunes as learning materials in English for Academic Purposes (EAP).