In an era demanding inclusive education, the conference theme "Unity in Music Education: Building Bridges for All" calls for innovative pathways to develop teacher competencies. This study addresses a critical gap in music teacher education: the transition from understanding differentiated instruction in theory to embodying it in practice. We propose that community music settings, with their inherent diversity and voluntary participation, serve as a powerful "pedagogical crucible" for this transformation.This qualitative case study aims to investigate how in-service music teachers' conceptions of differentiated instruction are reshaped through their facilitation of community music programs. The study will recruit 8-10 primary school music teachers with community music experience. Data will be collected through in-depth interviews and analysis of reflective journals, focusing on capturing pivotal moments and evolving understandings of student diversity.Grounded in theories of teacher identity and situated learning, the analysis seeks to illuminate the process of conceptual change. We anticipate findings that reveal a shift in teachers' perspectives: from viewing differences as a challenge to manage, to embracing them as a resource for collective creativity; and from a fixed, curriculum-centered teaching role towards a more flexible, facilitator identity.This research significance is twofold. Firstly, it contributes new insights into teacher professional development by highlighting community music as an essential, yet underutilized, learning context. Secondly, it proposes a tangible bridge between formal teacher education and the complex realities of diverse learning needs, directly supporting the conference's mission of building inclusive bridges through music education.