This research was aimed at studying how well an English textbook fulfills language content criteria suggested by Alan Cunningsworth's theory: Grammar, Vocabulary, Phonology, Discourse, and Style and appropriacy. The subject of the research was the Bahasa Inggris textbook for the twelfth grade of senior high school. This study used the descriptive qualitative method, which is also known as documentary analysis. The result shows that the textbook fulfills the majority of Alan Cunningsworth’s language content aspect criteria. The textbook reaches the final score of 79.48 percent. The teacher should supply another material from the other books. Also, to meet Alan Cunningsworth’s requirements for an excellent textbook, the author can revise the textbook