Textbooks have long been considered a pivotal learning and teaching resource in classrooms. However, there is a paucity of research on how teachers use textbooks in relation to their beliefs, with analytic methods in such studies mainly restrained to content-based thematic analysis. To this end, from the perspectives of Halliday’s (1994) systemic functional linguistics (SFL) and Vygostky’s (1978) socio-cultural theory (SCT), this book explores how a Chinese college English teacher acts upon his beliefs and uses textbooks to mediate his students’ English learning in his classroom.Drawing on constructs of the SFL-based appraisal and speech function as well as interview excerpts, the study reveals that in the textbook-based classroom the Chinese college English teacher acts upon his beliefs that are constructed by diverse contextual factors. Implications of this study include using SFL and SCT to explore educators’ beliefs and practices and also providing effective teacher education for Chinese college English instructors to reshape their beliefs so that they are better prepared to use textbooks in classrooms.