Book excerpt: The ability to produce and understand referring expressions is basic to human language use and human cognition. Reference comprises the ability to think of and represent objects (both real and imagined/fictional), to indicate to others which of these objects we are talking about, and to determine what others are talking about when they use a nominal expression. The articles in this volume are concerned with some of the central themes and challenges in research on reference within the cognitive sciences - philosophy (including philosophy of language and mind, logic, and formal semantics), theoretical and computational linguistics, and cognitive psychology. The papers address four basic questions: What is reference? What is the appropriate analysis of different referring forms, such as definite descriptions? How is reference resolved? and How do speaker/writers select appropriate referring forms, such as pronouns vs. full noun phrases, demonstrative vs. personal pronouns, and overt vs. null/zero pronominal forms? Some of the papers assume and build on existing theories, such as Centering Theory and the Givenness Hierarchy framework; others propose their own models of reference understanding or production. The essays examine reference from a number of disciplinary and interdisciplinary perspectives, informed by different research traditions and employing different methodologies. While the contributors to the volume were primarily trained in one of the four represented disciplines-computer science, linguistics, philosophy and psychology, and use methodologies typical of that discipline, each of them bridges more than one discipline in their methodology and/or their approach.