This book explores the nature of finiteness, one of most commonly used notions in descriptive and theoretical linguistics but possibly one of the least understood. Scholars representing a variety of theoretical positions seek to clarify what it is and to establish its usefulness and limitations. In doing so they reveal cross-linguistically valid correlations between subject licensing, subject agreement, tense, syntactic opacity, and independent clausehood; show how these properties are associated with finiteness; and discuss what this means for the content of the category. The issues explored include how different grammatical theories represent finiteness; whether the finite/nonfinite distinction is universal; whether there are degrees of finiteness; whether the syntactic notion of finiteness has a semantic corollary; whether and how finiteness is subject to change; and how finiteness features in language acquisition. Irina Nikolaeva opens the book by describing the history of finiteness and its place in current thinking and research. She then introduces the chapters of the book, comparing the authors' perspectives and showing what they have in common. The book is then divided into four parts. Part I considers the role finiteness plays in formal syntactic theories and Part II its deployment in functional theories and as the subject of research in typology. Parts III and IV look respectively at the finite/nonfinite opposition in individual languages and at the role finiteness plays in linguistic change and linguistic development. The book is written and structured to appeal to scholars and students of syntax and general linguistics at graduate level and above.