Relating visual images to textual messages may have great potential in facilitating students’ reading comprehension. The inevitable and important presence of visuals in textbooks obliges language teachers to exploit all semiotic resources to deepen students’ understanding. However, analysis of how images interact with text in textbooks has been rare, and among the efforts it has generally been found that visuals and text often fail to achieve coherence. This study investigates whether and how text and image complement each other ideationally by (...) six sense relations and interpersonally by the Mood system in ninth-grade English as a Foreign Language textbooks to reach intersemiotic complementarity. The results revealed that ideational rather than interpersonal IC is more frequent, where many more Participants than Processes in the texts find their visual complements. Ideational IC is particularly high in Information Reports while Recounts generally mark higher percentages of interpersonal IC. To accomplish ideational IC, repetition is most frequent, followed by hyponymy and collocation. Distinct IC patterns also characterize the different editions of textbooks investigated, which may suggest their different potentials in catering to students of varying proficiencies. (shrink)