This study was designed to firstly develop a corpus of Indonesia's junior high school (JHS) and senior high school (SHS) English textbooks (TB) and national examination (NE) texts. By means of corpus analysis, this study then attempted (1) to find out the vocabulary levels (i.e. distribution among the K1-K20, where K refers to 1000-word band in the BNC word frequency list) of JHS and SHS TBs and JHS and SHS NE texts; (2) to compare the lexical variety of JHS and SHS TBs and NE texts, (3) the number of interdisciplinary academic words, and (4) the number of words beyond the 2,000 high frequency English words the texts contained. Research results reveal that (1) JHS TBs belonged to K-4, K-5, and K-4 levels (i.e. knowing 4,000-5,000 words is necessary for the 95% comprehension of these texts) for Grades 7-9 respectively and SHS TBs belonged to K-4, K6, and K5 levels for Grades 10, 11, and 12 respectively; while the vocabulary levels of JHS NE texts belonged to K4- K5 and SHS NE texts belonged to K3-K5; on average the vocabulary levels of JHS TBs were lower than those of SHS TBs, whereas JHS NE texts levels were slightly higher than those of SHS NE texts; (2) the lexical variety of JHS TBs was the same as that of SHS TBs with the average index of 0,23; while the lexical variety of JHS NE texts was 0,27, which was lower than the SHS NE texts with 0,38; (3) for the words beyond the 2,000 basic words, the JHS and SHS NE texts covered 11.20% and 15.10% of the entire words, or higher than those of JHS and SHS TBs, which covered only 7.89% and 11.87% respectively; and (4) the same profile appeared in the interdisciplinary academic words (Coxhead's AWL), where JHS and SHS TBs contained 1.75% and 3.56% respectively, or lower than JHS and SHS NE texts, which contained only 3.26% and 5.65% respectively of all the tokens in the texts.