This presentation discusses a musical co-creation process conducted by three composers in direct collaboration with an instrumentalist, within a theatrical performance where music holds equal importance to text and dramaturgy. In this interdisciplinary context, the composer assumes the role of musical facilitator, actively embracing the creative decisions of the performer and dissolving the traditional hierarchy between them. Inspired by practices such as John Cage’s indeterminacy, John Zorn’s game pieces, and Cornelius Cardew’s open scores, the project emphasizes improvisation, collective negotiation, and active listening as essential tools. The traditional figure of the composer becomes diluted, giving way to a collaborative dynamic where composition is shared and shaped based on the performer’s initiatives. The developed methodology particularly highlights the importance of clearly and objectively describing sonic objects and gestures. To achieve this, it draws on theories of listening and sonic description proposed by Pierre Schaeffer and Denis Smalley, as well as Walter Thompson’s practice of soundpainting. These approaches underscore the linguistic challenge inherent in communicating musical ideas, mak- ing active listening crucial for effective and democratic dialogue between composers and performers. Finally, the presentation critically addresses the absence, within Portuguese music schools, of pedagogical models that transcend the binary perspective of com- position and performance. It argues that collaborative practices represent valuable educational alternatives capable of fostering horizontal, experimental, and creative musical learning.