Conflict and violence in animal societies, by C. H. Southwick.--Aggressive behavior among vertebrate animals, by N. E. Collias.--Aggressive behavior and evolution, by N. E. Collias.--Fighting, by N. Tinbergen.--What aggression is good for, by K. Lorenz.--Aggression in social insects, by D. I. Wallis.--Agonistic behavior of mice and rats: a review, by J. P. Scott.--Aggression in monkey and ape societies, by K. R. L. Hall.--Physiologic factors in aggressive behavior, by D. E. Davis.--Chronic physiological effects of fighting in mice, by F. H. Bronson and B. E. Eleftheriou.--The neural control of aggression, by J. L. Brown.--Some aspects of brain biochemistry correlated with general nervous reactivity and aggressiveness, by B. L. Welch and A. S. Welch.--Effects of isolation on maternal aggressiveness and body growth rates of offspring, by A. S. Weltman, A. M. Sackler, R. Schwartz, and S. Stroman.--Genotypic factors in the ontogeny of behavior, by B. E. Ginsburg.--Genetic and environmental variables influencing animal aggression, by C. H. Southwick.