This book provides an overview of the nascent field of information pooling and group judgmental accuracy. The contributors to this volume include mathematical psychologists, economists, social psychologists, political scientists, and statisticians. The book is organised around five review essays: one on information pooling from the perspective of models of individual judgment (Batchelder), one on information pooling and group judgment (Grofman and Owen), one on group judgment in applied settings (Hastie), and one on organisational design (Radner). Along with the review essays discussant comments are also provided which elaborate on points not covered in the essays. While the focus of these papers is largely theoretical and abstract, the subject of information pooling and optimal group judgment is clearly one of great practical importance and is directly relevant to issues of policy choice and organisational structure.