Four papers pertaining to the concept of pro/antisociality and the biosocial perspective outline the basic assumptions of this perspective, conceptualize pro/antisociality within this perspective, identify behavioral and demographic variables that correlate with criminality, and discuss the extent to which social scientists and criminologists currently subscribe to the biosocial perspective. Six papers examine how various aspects of evolutionary and genetic factors may contribute to variation in criminality and other pro/antisocial behavior patterns. One paper argues that criminal behavior may have evolutionary roots, and another contends that genetic and evolutionary factors may even underlie the emergence of the criminal justice system. Five papers discuss how brain functioning may relate to pro/antisociality. Two papers consider how sex hormones alter brain functioning in ways that affect the probability of persistent criminality and aggression. Two perspectives presented relate to how arousal-control processes in the brain may predispose persons to varying degrees of pro/antisocial behavior. Papers on biosocial theorizing about criminality argue that both evolutionary and neurochemical factors have an etiological role in prosocial behavior and that persons prone to crime and delinquency may have unusual chemical reward systems and brain circuits that reinforce their actions. Chapter references and name and subject indexes