The discussion of biological research pertaining to violence considers genetic factors, which have been analyzed in animal research; family, twin, and adoption studies; and studies of chromosomal abnormalities. Other biological research reviewed considers antisocial behavior linked to the functioning of the autonomic nervous system and the central nervous system. Epileptic disorders and brain disorders are mentioned. Biological influences on aggression discussed are chemical substances in the body, diet, body structure, and complications during pregnancy and delivery. Psychoanalytic explanations of violence are discussed from the perspective of psychological forces that produce instrumental violence. Consideration of psychological theories applied to aggressive and violent behavior includes frustration-aggression hypotheses, social learning theory, and stress formulations. The use of personality assessments to identify violence-prone persons is briefly mentioned. The review of sociological approaches to the study of assaultive behavior considers subcultural perspectives, structural (strain) theories, and interactionist (situational) hypotheses. Fifty-three references are listed.