The Ecology of Social Behavior explores the relationships between ecology and the origins and maintenance of social behavior. The chapters in this book suggest that a consideration of ecological factors is necessary to any paradigm that tries to explain the origins and maintenance of social behavior. Most also suggest that there are some trade-offs between ecology, genetics, and phylogeny in the development and persistence of specific social systems. The book is organized into five parts. Part I provides an overview of the main themes covered in the present volume. Part II contains papers on ecological interactions, including variation in group sizes of forest primates, group foraging, and the origin of monogamy in mammals and fishes. Part III examines the ecology of social mammals. These include the ecological conditions for philopatry and the relationship of habitat variability to sociality in yellow-bellied marmots. Part IV focuses on the ecology of social birds while Part V deals with the ecology of social arthropods.