A growing body of empirical research reveals that genetic factors account for a substantial amount of variance in measures of antisocial behaviors. At the same time, evidence is also emerging indicating that certain environmental factors moderate the effects that genetic factors have on antisocial outcomes. Despite this line of research, much remains unknown about the specific environments that may moderate genetic influences on adolescent delinquent involvement and victimization. The current study addresses this gap in the literature by examining whether 13 criminogenic environments alter the extent to which genes influence delinquency and victimization. Analysis of sibling pairs drawn from the National Longitudinal Study of Adolescent Health revealed significant environmental moderation of genetic influences on measures tapping serious delinquency, violent delinquency, and personal victimization. In general, greater exposure to criminogenic risk factors increases the effects that genetic factors have on these three antisocial outcomes. The implications that these findings have for criminological theory and research are discussed. (Contains 1 figure and 5 tables.)