This study explores Taiwanese mathematics teachers’ critiques of a series of geometry textbooks for grades 8 and 9. Two hundred seventy-four critiques from 143 mathematics teachers were analyzed by referring to six attributes of abstraction. Through analysis and interpretation of these critiques, the meaning of each attribute was refined, and their features were revealed. Possible beliefs-in-critiquing related to the features were discussed. This study contributes to the literature by advancing understanding of mathematics teachers’ critiques of textbooks. We conclude with a discussion of the methodological and educational implications of teachers’ critiques as well as how critiques of teaching materials can influence teacher education.