Textbook evaluation plays an important role in ELT. Thus, different textbook evaluation checklists have been proposed to evaluate ELT textbooks. Among these, there are mainly two types of evaluation: a predictive evaluation and a retrospective evaluation. While predictive evaluation is done by the teachers to decide which textbook to use, retrospective evaluation is done theoretically or empirically as an action research to arrive at a final decision about the textbook. Thus many of the textbook evaluation guidelines in the literature have been proposed to evaluate textbooks either to decide on which textbook to use or to judge the effectiveness of the textbooks that have already been used. While some of these checklists are too complicated for the teachers, the others are superficial and neglect the overall criteria to cover all of the points. This paper aims to develop a comprehensive textbook evaluation checklist to evaluate ELT textbooks. The checklist consists of six components, namely, practical considerations, language content, design and organization, language skills, exercises and activities, cultural considerations. Each of these components is investigated and specific criteria are suggested to evaluate these components of ELT textbooks. This textbook evaluation checklist can be used both as a predictive evaluation and a retrospective evaluation. Accordingly, as a predictive evaluation guide, it will help the teachers to decide on which textbook they will use and at the same time as a retrospective evaluation guide, it will be useful to evaluate the effectiveness of the textbooks that the teachers have used. Thus it is hoped that teachers and researchers can make use of this checklist to evaluate the textbooks that they will use or they have used so far.