Volume 31 of Reviews in Mineralogy reviews current thinking on the fundamental processes that control chemical weathering of silicates, including the physical chemistry of reactions at mineral surfaces, the role of experimental design in isolating and quantifying these reactions, and the complex roles that water chemistry, hydrology, biology, and climate play in weathering of natural systems. The chapters in this volume are arranged to parallel this order of development from theoretical considerations to experimental studies to characterization of natural systems. Secondly, the book is meant to serve as a reference from which researchers can readily retrieve quantitative weathering rate data for specific minerals under detailed experimental controls or for natural weathering conditions. Toward this objective, the authors were encouraged to tabulate available weathering rate data for their specific topics. Finally this volume serves as a forum in which suggestions and speculations concerning the direction of future weathering research are discussed.