This study aims to develop a textbook evaluation tool by which school teachers can use to select government-authorized English textbooks. It first developed evaluation areas, standards, sub-standards, and scales for which a delphi technique and a survey were conducted. Twelve textbook professionals and eleven school teachers participated in this development stage of the textbook evaluation tool. Then ten English school teachers used the textbook evaluation tool with an English textbook and identified problems in applying the tool to real school settings. The validity of the tool was also statistically examined. Drawing upon the opinions of the textbook professionals and the school teachers, and the statistic results, the study completed the English textbook evaluation tool. The tool has 6 evaluation areas, 17 standards, 40 sub-standards, and 5 point scales. The areas are Curriculum, Content Selection, Content Organization, Teaching-Learning Methods, Assessment, and Graphic Layout and Orthography. Each evaluation area has two or four evaluation standards. A standard consists of two or three sub-standards. Every sub-standard has a scale of five points. This study provided policy suggestions for successful implementation of the English textbook evaluation tool in schools.