This article reports on a study investigating the textbook evaluation techniques of novice and experienced teachers, which was conducted by the Language Teaching Expertise Research Group (or LATEX) within Lancaster University's Department of Linguistics and English Language. Three ELT teachers were chosen to evaluate the student and teacher editions of a newly-released ELT textbook using the technique of concurrent verbalization. The results of the research add to the growing body of knowledge on expertise, providing insight into the differences between the teachers with respect to their various evaluation strategies. They also point to implications for the development of teacher education and training.