Understanding the language demands made on students can help teachers provide pedagogical support during critical transition periods, in turn helping English learners make a smooth transition to the next stage in their education. Through multi-stratal analysis of English textbooks in Hong Kong, this paper elucidated the differences in language demands made of students in different grades, particularly in terms of scope and complexity of choices in register and lexico-grammar. The analysis revealed two critical transition periods: the move from primary to junior secondary school and from junior secondary to senior secondary school. Different linguistic demands during these two transition periods require additional pedagogical support. Furthermore, this paper found a close correlation between the registerial progression indicated by the analysed texts and the learning targets for grades in the mandated English language curriculum. The lexico-grammatical progression revealed contributes to understanding the meaning of more complex stressed in the mandated curriculum. Copyright ©2021 Elsevier.