This volume considers the role comets may have played in the origins and evolution of life, particularly in light of recent investigations of Halley's comet, of new insights into organic synthesis in meteorites and comets, and of new results of numerical simulations of cometary orbits and impacts on Earth. The book is intended as a comprehensive review of current research, accessible to graduate students and others new to the field. Each chapter was prepared by an expert to give an overview of an aspect of the field, and carefully revised by the editors for uniformity in style and presentation.