This study examined how gender and development (GAD) concepts and principles are incorporated into English 10 learning materials using a mixed-methods approach. The examination of lesson plans and self-learning modules through content analysis revealed biases supporting traditional gender roles, such as inadequate representation of women and showing stereotypical gender behaviours. Interviews with English 10 public teachers highlighted diverse strategies they employed, despite limited exposure to GAD concepts, suggesting a lack of comprehensive training in this area. However, teachers still endeavour to integrate these principles into their instruction to foster inclusivity, though challenges persist, such as biases influencing disciplinary measures. The findings of this study highlight the importance of challenging narrow views and promoting inclusive practices in educational materials. This study contributes to the ongoing efforts to promote gender equality and diversity in education highlighted in UNESCO’s Education for All initiative (2003), emphasizing the need for continuous awareness, sensitivity, and proactive integration of GAD principles in educational settings.