Textbooks are one of the essential teaching materials in learning activities. This study examines the English textbook "Bahasa Inggris Tingkat Lanjut Untuk SMA/MA Kelas XI Semester 2" in relation to Tomlinson's principles (2011). The research aims to determine whether or not the textbook meets the criteria for a good English textbook based on Tomlinson's principles. A qualitative approach was used in this research, employing descriptive content analysis as the analytical framework. Data collection involved reviewing textbook content, while analysis included an objective assessment of the content based on Tomlinson's sixteen criteria for effective learning materials. This study focuses on the content of the textbook, examining elements such as impact, learner comfort, confidence-building, relevance, language exposure, and diversity of materials. The findings of this study suggest that the English textbook for eleventh-grade students identified 14 of 16 Tomlinson's principles, including impactful materials, relevant content, student engagement, and diverse learning opportunities, presenting authentic language use. This analysis has a significant impact on selecting textbooks that align with the pedagogical framework, aiming to enhance student learning outcomes.