The purpose of this paper is to examine the level-appropriateness of listening tasks in middle-school English activity books, which have been used in Korean secondary schools since 2009 in order to facilitate level-differentiated learning. Five different kinds of middle-school English activity books from grade 1 to grade 3 (i.e., 15 in total) were randomly chosen for analysis. It was found that the listening task difficulty of activity books as a whole became greater as the proficiency level went up, which implied listening tasks were well sequenced regarding the proficiency level. Some activity books, however, showed a problem with sequencing listening tasks in terms of difficulty because the task difficulty in the higher grade was lower than that in the lower grade. In terms of listening task difficulty, in addition, activity books were not homogeneous even in the same level. Implications of the findings for the level– appropriateness of listening tasks and further research into listening task difficulty are discussed.