Since the early twentieth century, Shanghai has sustained a vibrant jazz ecosystem that continues to shape school music education and young people’s perceptions of musical identities. Although many papers indicate that popular music pedagogy is not encouraged in Chinese schools, a year of involvement in an international school in Shanghai revealed abundant popular music activities—especially in jazz—offered informally within the school context. This study aims to examine how integrating informal jazz learning into a formal international school context in Shanghai influences equitable access, participation, recognition, outcomes, and students’ musical identity exploration and commitment. Grounded in Erikson’s psychosocial theory and Marcia’s identity status model, this mixed-methods case study combined year-long observations of school jazz activities with semi-structured interviews with 10 participants aged 16-25 (current students and recent alumni, including school jazz band members, self-identified jazz enthusiasts, and students pursuing jazz degrees in the United States). I analyzed the roles of digital learning, peer learning, and assessment practices in facilitating or constraining engagement and identity work. Findings indicate that informal strategies broadened entry into jazz and supported musical identity exploration; however, limited assessments and uneven recognition from parents and the broader community constrained identity consolidation and access to high-status opportunities. This work addresses a research gap in secondary-school jazz education in Chinese context and has implications for the design of more equitable, identity-affirming music programs.