The modern fields of information retrieval and computational linguistics reflect the significant contributions of one researcher, Karen Sparck Jones, a dominant figure in both fields. Her work is characterized by a strong inclination to learn about language from usage as well as by a careful and thorough approach to experimental evaluation. Collected here are all of Sparck Jones's major works, spanning four decades. Advances in computer performance and the increasing availability of electronic text have helped realize her early research ideas, and her ideas continue to stimulate groundbreaking work. Sparck Jones lived long enough to plan this volume and draft its introduction, now completed by Ann Copestake and Stephen Robertson.