This article expands upon my previous work titled ‘Diahemitonic Modality: A Quarter-Tonal Composition System’ and in which I mapped the diatonic modal system onto quarter-tonality. As tonality derives from modality and modality has been successfully mapped onto quarter-tonality, the prospect of extending this mapping to tonality becomes conceivable. The design process mirrors that of diahemitonic modality, now focusing on tonal harmony and encompassing considerations of scale, mode, key, interval, chord, function, cadence, sequence and modulation. The one-to-one mapping of each aspect of diatonic tonality onto the quarter-tone scale culminates in diahemitonic tonality.