摘要：Understanding the vocabulary contained in a book is the door to a complete understanding of the book. The percentage of vocabulary that is understood will be a marker of whether the material in the book is understood by students or not. With this background, research on students' vocabulary understanding of Indonesian textbooks is important. This research is the first step in the research on vocabulary enrichment book development. The approach taken is quantitative with descriptive methods. The data collection technique used a survey with an instrument in the form of a questionnaire. Respondents in this study were 7th grade, 8th grade, and 9th grade students in the junior high school. The results of the study were in the form of a vocabulary profile and students' vocabulary understanding. Seventh grade textbooks have a vocabulary type of 6,220 with a token of 50,051, eighth grade textbooks have a vocabulary type of 6,301 with a token of 46,904 and ninth grade textbooks have a type of vocabulary of 5,018 with a token of 33,926. In 7th grade there are 2,746 or 44% of the vocabulary with the frequency of using it only once written. Meanwhile, in 8th grade there are 2,901 or a total of 46% vocabulary and in 9th grade there are 2,897 or 58% vocabulary with a frequency of written usage only once. From the research results it was also known that a number of 88% percent of students had experienced difficulty understanding vocabulary. In addition, from 200 randomly selected vocabularies, it is known that the percentage of vocabulary commonly used by students is only 28% in 7th grade, 31% in 8th grade, and 39% in 9th grade. These results indicate that further research is needed on the development of enrichment books that can improve students' understanding of vocabulary..
