This study examined the organization and distribution of sequence expansions in the dialogs of the Top Notch ESL textbook series through the lens of Conversation Analysis (CA). The research aimed to identify the presence, types, and frequency of sequence expansions across the four books of the series. A total of 132 dialogs were systematically analyzed and categorized according to their sequential structure. The analysis revealed that while some examples of sequence expansions are present, their representation is limited and uneven. Certain types, including pre-offers, pre-announcements, interest-type non-minimal post-expansions, and repair-type non-minimal post-expansions, were entirely absent. The majority of the dialogs relied on base adjacency pairs, typically in the form of question–answer exchanges, with evaluative minimal post-expansions being the most frequent. The findings indicate that the Top Notch series does not fully reflect the sequential and interactional characteristics of natural conversation, as it lacks systematic application of CA principles in dialog construction. Although the total number of expansions suggests some inclusion of interactional patterns, the absence of key types limits the pedagogical value of the materials in promoting authentic communication. These results emphasize the need for textbooks to incorporate CA-informed dialog design that mirrors the turn-taking mechanisms and sequence organization found in real discourse. Pedagogically, the study suggests that teachers should supplement textbook dialogs with authentic conversational data and explicitly raise learners’ awareness of sequence structures, turn-taking, and repair mechanisms. Moreover, textbook authors are encouraged to integrate a wider range of sequence expansion types to ensure a more realistic representation of spoken interaction. Finally, the study acknowledges several limitations, including its focus on written dialogs and a single textbook series. Future research is recommended to examine other ESL materials, explore underrepresented conversational structures, and compare textbook dialogs with naturally occurring conversations. By doing so, future studies can contribute to the development of more communicatively authentic and pedagogically effective ESL textbooks.
