1. Introduction（頁93-94）；

2. Literature Review（頁94-99）；

3. Research Methodology（頁99-101）；

4. Findings（頁102-121）；

5. Discussion（頁121-123）；

6. Conclusion（頁124）；

References（頁124-126）；

Appendix A: A List of Analyzed Textbooks（頁127）；

Appendix B: Figures (Biographies) in the Textbooks（頁128-130）

This corpus-based study investigated the transformation of English from an elite to a mass language as portrayed in textbooks used by five generations in Taiwan (ages of 20-69 years). By analyzing 989,629 tokens from 1921 lessons across 33 editions at elementary, junior high, and high school levels—from the 1960s to the 2010s—the study revealed distinct generational trends. Notably, the textbooks of the oldest generation, who experienced an era of elitist secondary education, exhibited more complex and extensive content than did textbooks for the generation now in their 40s and 50s. Notably, the textbooks for the generation now in their 20s had more content and a higher complexity level than did those used by the generation now in their 60s. The origin of the stark complexity gap between junior high and high school might be attributed to the 1968 implementation of compulsory education, a disparity that persists despite the introduction of English at the elementary level. Finally, the study recommends that curriculum designers should increase content quantity while reducing complexity in high school English textbooks to facilitate a smoother transition from junior high to high school.