Learning support materials, including commercially prepared textbooks, play a central role in the implementation of a new curriculum. In South Africa, classroom resource materials such as textbooks are reported to have had a considerable influence on Teachers' pedagogical practices. The aim of the article is to explore the criteria that Grade 9 teachers use for the selection of technology textbooks. The data were purposefully collected from technology teachers at ten schools in the Tshwane South and Tshwane North districts through semi-structured interviews. The linguistic notion of textbook register was used to classify the selection criteria used by teachers according to the field, mode and tenor of the textbook. Results indicate that when technology teachers select textbooks they mainly use criteria related to the field (the nature of the content of the text) and the mode (the way the content is presented) of the book. Few criteria relate to relationships conveyed by the book (the tenor) which is expressed as the extent to which it provides teacher support and the influence it allocates to the student. The findings confirm the high frequency of the use of criteria in the area of breadth, depth and accuracy of content knowledge and, less frequently, its progression and relationship with students' everyday experiences. Selection criteria related to activities presented in the book include the number and detail of practical activities and design tasks, and the variety and the relevance of activities with respect to the content knowledge presented. A concern with the quality of communication of a book is more often expressed in selection criteria for illustrations than for language difficulty. Lastly, criteria for selecting textbooks do hardly focus on the teaching strategies in the book, and infrequently on the guidance for lesson planning and assessment. However, several teachers select texts on the basis of the opportunities for tailoring information and activities specifically for their students' contexts.