This study was conducted to determine the vocabulary coefficients of the themes in 7 Turkish textbooks taught during the 2019-2020 academic year. The study of the vocabulary coefficients of the themes is a method specific to the claim of the research. There are subject scopes and concept areas specific to the themes in the Turkish textbooks. The texts of themes were selected according to the concept subject scope and concept areas. As the vocabulary coefficients of the selected texts vary accordingly, the vocabulary coefficients of the Turkish textbooks were calculated thematically. The results showed that the vocabulary coefficients of the Turkish textbooks were low. It was observed that none of the themes of the 7 textbooks examined had vocabulary coefficients at the level of good or very good. It was understood that the Turkish textbooks were not sufficient in teaching vocabulary to students and that the Turkish curriculum was insufficient to realize the predicted learning outcomes. The vocabulary coefficients of the themes in the examined textbooks were as follows: 0.3370475 in the 5th grade Turkish textbook by Anittepe publishing, 0.3021508 in the 6th grade Turkish textbook of Ministry of National Education (MONE) publications, 0.33444094 in the 6th grade Turkish textbook of Ekoyay publishing, 0.3327491625 in the 7th grade Turkish textbook of Özgün publications, 0.348125375 in the 7th grade Turkish textbook by MEB, and 0.321079125 in another Turkish textbook by MEB (Editor Emine KIRMAN). It was concluded that coefficient of the themes of the 8th grade Turkish textbook examined was 0.334793675.