Vocabulary mastery is very important for measuring the elementary-school students’ achievement.. The amount of vocabulary in the student book reflects the standard of proficiency vocabularies should be achieved for certain level. This study aims to describe the development of vocabulary in the books of early-grade elementary-school students (level 1, 2, 3) and shows the number of vocabularies. Each level has eight books/themes. Therefore, this study uses 24 books. In this study, we apply lema ‘entry’ application as the documentation method. The results of the study showed that the highest number of vocabularies is in grade 3 theme 7, the least is in grade 1 theme 6. The highest of vocabulary in grade 1 is 2105 (theme 3), grade 2 is 2328 (theme 5), and grade 3 is 2383 (theme 7). The development of vocabulary does not always rise from one theme/level to the theme/class above it. Writing books for the student should consider increasing vocabulary, not just the number of words or pages.
Development of vocabulary, elementary school,