Categories of the verb in natural languages include tense, aspect, modality (mood) and voice. Among these, voice, in its rich and diverse manifestations, is perhaps the most complex. But most prior research concentrates on only certain types, predominantly passives. Voice expresses relations between a predicate and a set of nominal positions - or their referents - in a clause or other structure. Grammatical Voice is the first typological study of voice systems based on a multi-language survey. It introduces a threefold classification of voice types, in the first place distinguishing passivization phenomena (derived voice) from active-middle systems (basic voice); and further, distinguishing each of these from pragmatically grounded voice behaviours, such as focus and inverse systems. As the first comprehensive study of voice systems and voice typology, this book makes a significant contribution to current research in linguistics and grammatical theory.