insight into group reasoning and the "we-mode" approach, which is used to account for collective intention and action, cooperation, group attitudes, social practices, and institutions as well as group solidarity. This book will be of interest to a wide range of readers and graduate students and researchers interested in contemporary philosophy of sociality, sociological theory, social ontology as well as the philosophy of mind, decision and game theory, and cognitive science. Tuomeläs book stands as a model of excellence in social ontology, an especially intractable field of philosophical inquiry that benefits conspicuously from the devotion of Tuomeläs keen philosophical mind. His book is must reading in social ontology. J. Angelo Corlett, Julia Lyons Strobel