Surveying and critically synthesizing the research literature Krause (behavioral ecology U. of Leeds UK) and Ruxton (behavioral and physiological ecology U. of Glasgow UK) explore the mechanisms that govern the evolution and maintenance of grouping behavior in the animal kingdom and the ecological factors that control group size and group composition. Although the emphasis is on the functions of grouping developmental evolutionary and mechanistic aspects are also discussed. Annotation (c) Book News Inc. Portland OR (booknews)