This volume offers detailed accounts of current research in grammatical number in language. Following a detailed introduction, the chapters in the first three parts of the book explore the multiple research questions in the field and the complex problems surrounding the analysis of grammatical number: Part I presents the background and foundational notions, Part II the morphological, semantic, and syntactic aspects, and Part III the different means of expressing plurality in the event domain. The final part offers fifteen case studies that include in-depth discussion of grammatical number phenomena in a range of typologically diverse languages, written by - or in collaboration with - native speakers linguists or based on extensive fieldwork. The volume draws on work from a range of subdisciplines - including morphology, syntax, semantics, and psycholinguistics - and will be a valuable resource for students and scholars in all areas of theoretical, descriptive, and experimental linguistics.