This research is an inquiry into how architecture can inform the practice of composition. As an architect and composer, I try to find strategies for musical composition In architectural practice and thought, by reframing and confronting concepts from both disciplines. My research aims at an expanded practice (and analysis) of musical creation that transverses different conceptions of space-from the score based pitch space to the social and political spaces of music's production, performance and reception. This practice based PhD research consists of a portfolio of nine works that were developed in a dialectical relation to these ideas. The works are presented in a framework composed of five conceptual tools used to articulate music and architecture. These are; Material, Site. Drawing, Programme and Use. With the notion of Material. I explore how the acoustic behaviour of a performance space, or of a performatlve device' affects the musical work. Architectural materials become musical ones as they are implicated in the listening experience. The discussion about Site brings to music the notions of place. the local, and everyday life, embracing soundscapes so many times excluded from musical discourse. Musical sites are also architectural sites, always related to their present environment, and their everyday contlngenclt;ls. Drawing Is a tool for developing ideas, but also the main mediator between architect and builder. or composer and performer. Programme exposes the constraints and conditions of the creation process, while also revealing the sociopolitical relations between musicians and audiences, institutions and composers, composers and performers. Programming as framing can be a platform to expand what the work concerns. Through a consideration of Use, the work becomes dispersed in a pJurality of agents that converge in a useful event. Thus composition. as architecture, moves from being about conditioning design to designing conditions where musical events may happen.