Application of critical discourse analysis (CDA) models for investigation of textbooks’ different aspects and characteristics has been widespread in recent years. The aim of this study was to conduct CDA on Iranian textbooks series Vision, the official textbooks used nationwide in high schools, for the purpose of identifying and examining the textbook’s ideological and sociocultural aspects, underlying system of values and level of authenticity. To this end, Fairclough’s three-dimensional model of CDA was employed to explore these areas in the contents of the three textbooks. The results showed that the textbooks had been developed based on traditional and state-approved ideological elements of Islamic and Iranian culture, as intertextually reflected in major legislations, regulations and standards of the national education system, and in line with public education policies. Among the significant values presented and endorsed in the textbooks' contents were patriotism and nationalism, environmental protection, seeking knowledge and hard work. Important themes and topics included references to Iranian culture and patriotic or nationalistic concepts, history of Iran, famous Iranian figures, nature and environment, encouraging curiosity and quest for knowledge, references to religious beliefs, preference for outdoor activities, health, healthcare and schooling. Also, there was predominance of male characters and more frequent occurrences of representations of male gender. Arguments in support of the claim that the textbook contents have low authenticity and limited relevance can be made in light of the textbooks' conversations contexts and depicted situations or scenarios of language use, themes and topics, tasks and activities, as well as the absence of English-speaking culture and identity.
