While recent techniques of digital sound synthesis have put numerous new sounds on the musician's desktop, several artificial-intelligence (AI) techniques have also been applied to algorithmic composition. This article introduces Vox Populi, a system based on evolutionary computation techniques for composing music in real time. In Vox Populi, a population of chords codified according to MIDI protocol evolves through the application of genetic algorithms to maximize a fitness criterion based on physical factors relevant to music. Graphical controls allow the user to manipulate fitness and sound attributes.