Commonly defined as the quartet of metallophones that accompanies Balinese shadow puppet theater, gender wayang is widely described as “the music for wayang.” Yet in twenty-first-century Bali, this definition is increasingly partial. Gender wayang now circulates through extracurricular school programs, arts competitions, banjar and sanggar initiatives, radio and television broadcasts of the Puja Tri Sandhya mantra, commercial recordings, and experimental compositions. While these developments suggest vitality, they also raise a central question: what, precisely, is being sustained? Drawing on Huib Schippers’ ecological “Five-Domain Framework,” and engaging scholarship by Lisa Gold, Ako Mashino, and Brita Heimarck, this paper argues that development and sustainability within the gender wayang complex are paradoxically intertwined. Rather than equating sustainability with the number of performers or new compositions, I examine four interrelated domains, systems of learning, musicians and communities, contexts and constructs, and media and infrastructures, to assess how change simultaneously enables and endangers distinct dimensions of the tradition. Standardization in formal education, competition repertoires detached from puppetry, shifting ritual practices, gender inclusion, and expanding media circulation have broadened participation while narrowing regional repertoires and weakening links to dramatic function. By disentangling these processes, this paper reframes sustainability as a multi-layered condition rather than a binary of loss or survival. For ethnomusicology, this case underscores the need to theorize development as both generative and erosive, to interrogate what stakeholders value as “tradition,” and to foreground context, power, and mediation in analyses of musical change.