This volume offers theoretical and descriptive perspectives on the issues pertaining to ergativity, a grammatical patterning whereby direct objects are in some way treated like intransitive subjects, to the exclusion of transitive subjects. This pattern differs markedly from nominative/accusative marking whereby transitive and intransitive subjects are treated as one grammatical class, to the exclusion of direct objects. While ergativity is sometimes referred to as a typological characteristic of languages, research on the phenomenon has shown that languages do not fall clearly into one category or the other and that ergative characteristics are not consistent across languages. Chapters in this volume look at approaches to ergativity within generative, typological, and functional paradigms, as well as approaches to the core morphosyntactic building blocks of an ergative construction; related constructions such as the anti-passive; related properties such as split ergativity and word order; and extensions and permutations of ergativity, including nominalizations and voice systems. The volume also includes results from experimental investigations of ergativity, a relatively new area of research. A wide variety of languages are represented, both in the theoretical chapters and in the 16 case studies that are more descriptive in nature, attesting to both the pervasiveness and diversity of ergative patterns.