The volume’s central concern is grammatical voice, traditionally known as diathesis, and its classical manifestations as Active, Middle, and Passive. While numerous problems in the meaning, syntax, and morphology of these categories in Indo-European remain unsolved, their counterparts in more exotic languages have raised still further questions. What discourse functions and diachronic events unite ‘voice’ as a recognizable phenomenon across languages? How are they typically grammaticalized? What stages do children go through in learning them? How does ‘voice’ link up with ergativity and with other categories and constructions such as the Inverse and the Antipassive?The authors in this volume have different perspectives on these problems: they discuss voice, e.g., from a typological-universal view, in relation to language acquisition and to ergativity, and from diachronic and cross-linguistic perspectives.