How can a computer help a person compose music, especially if the person has no prior musical training? This problem can be viewed from different perspectives—from developing the musical algorithms that the computer uses to automate the compositional process to designing the right interface for humans to interact with the machine. Hyperscore is a software tool that attempts to address both of these questions. It is a graphical composition environment that interprets the gestures of the strokes and lines the user draws in an intuitive way. The user can pen musical ideas, store them for later use, and create new pieces—all in one expansive canvas. The graphical elements in the drawing are mapped to musical structures, allowing the user to interweave and shape musical voices and define harmonic progressions visually. Hyperscore is a central element in workshops and live performances for the City Symphony projects.