Choosing which vocabulary to teach in an English classroom can be difficult, as many variables such as textbook content and student needs factor into the decision. To aid English instructors in this task, various word lists such as frequency bands from large corpora, research-based word lists, and proficiency levels can be consulted. However, it is not clear which (if any) of these sources are appropriate for any given language classroom, or what subset of the large lists should be taught. This paper attempts to shed light on this complex issue by conducting a case study analysis of textbook materials and student needs in an English for Academic Purposes (EAP) course at a university in Thailand. Reading passages from the course textbook and the vocabulary lists which accompany the texts were compared with the words which the students chose as being important for them to learn. The results of the case study showed that for this textbook and these students, the Common European Framework of Reference (CEFR) B2 level was an appropriate place to look for additional vocabulary. Although these results are specific to one course in one context, they showcase online tools that instructors can use to analyze their own classroom content and student needs, as well as describing generalizable insights that should be considered when choosing textbooks or creating class materials elsewhere.