This book makes an important contribution to the expanding body of work in generative phonology which aims to reduce the number of traditionally recognized melodic categories in order to achieve a greater degree of restrictiveness. By analyzing data from a large number of different languages, Nasukawa establishes a clear affinity between nasality and voicing, and demonstrates the advantages of treating these two properties as different phonetic manifestations of a single nasal-voice category. The choice of whether to interpret this category as voicing or nasality is determined by the active or inactive status of a complement tier; when active, this complement tier enhances the acoustic image of its head category and is interpreted as voicing. This study deepens our understanding of the typological relation between nasality and voicing, and sheds new light on a number of related agreement phenomena such as nasal harmony, postnasal voicing assimilation, voiced-obstruent voicing assimilation and spontaneous prenasalisation.