EAP is usually considered to be a branch of ESP, along with English for Professional Purposes (EPP) and English for Occupation Purposes (EOP). In that sense, as with all ESP, the EAP teaching content is explicitly matched to the language, practices and study needs of the learners. Most definitions of ESP (e.g. Robinson, 1991, pp. 2-5; Dudley Evans & St John, 1998, pp 4-5) include the following essential feature: ESP is goal directed and based on an analysis of needs.
For that reason, any ESP course needs to specify as closely as possible exactly what it is that the learners have to do through the medium of English, and therefore what their purpose is in learning English. A central role of the EAP lecturer or course designer, then, is to find out what the learners need, what they have to do in their academic work or courses, and help them to do this better in the time available.
Every EAP course is therefore different, as every student has different needs, and therefore needs to be designed from scratch. What, therefore, can the role of a published textbook be in this process?