Lexical make-up of the revised Engage with English textbooks utilized in Omani high schools for grades 11 and 12 are under examination. The textbooks were examined through a corpus-based methodology, employing the Vocabulary Profiler to classify terms put on the General Service List (GSL), the Academic Word List (AWL), and off-list vocabulary. The results indicate that the textbooks develop foundations in high-frequency vocabulary, they may inadequately prepare students to master Academic English, particularly due to the limited inclusion of AWL terms and the excessive presence of off-list vocabulary. These findings underscore the necessity of employing a balanced vocabulary strategy in textbook design to guarantee that students cultivate both communicative and academic competencies. Our study has some implications for English language teaching in Oman and recommendations for enhancing vocabulary training. © Pathan H., Aleksandrova O.I., Alvi U.F., Khalid M., 2025.