This study explores the co-development of music theory resources for Grades 7 and 8 at the Malta School of Music using a case study methodology. The first author collaborated with learners to create and refine music theory guides, testing sample chapters in classrooms and incorporating iterative feedback. Data collection included focus group interviews with two learner cohorts and an analysis of learner compositions to understand their experiences with the material. The findings highlighted four key themes for enhancing music theory education: (1) engaging learners through composition and performance, (2) integrating singing and collaboration, (3) deepening understanding through historical context and (4) enriching learning with a diverse repertoire. The study emphasises that music learners can play a salient role in developing inclusive music theory resources that are relevant beyond the classroom. The paper concludes with recommendations for future research, advocating for the integration of diverse musical genres, digital tools, collaborative learning, historical and cultural contexts and a repertoire that includes varied composers and performers. Additionally, portfolio-based learning is suggested as a means to support a more comprehensive approach to music theory education. These insights aim to make music theory more engaging, inclusive and applicable to students' personal and professional musical experiences.