This chapter reviews the evidence for genetic and environmental influences, both specified and unspecified in antisocial behavior. It discusses heritability of both adult and child mental disorders in DSM-IV-TR, for which antisocial behavior is central to their diagnosis. The chapter also reviews heritability of the related externalizing disorders. It highlights some of the most exciting new directions in this field, which aim to unpack the genetic and environmental black boxes in antisocial behavior, and provides the complexities of the gene-environment interplay in antisocial development. Evidence of genetic influences on antisocial behavior does not implicate that individuals exhibiting antisocial behavior are immune or resistant to interventions. Future research with combined approaches from behavior genetics and neuroscience will lead to better understanding of specific genes that result in structural and functional brain impairments that in turn give rise to antisocial, violent, and psychopathic behavior.