Despite assiduous efforts to eliminate it, antisocial behavior is still a problem. Approximately 20 percent of people in the developed world experience victimization by perpetrators of violent and non-violent illegal behavior each year (US Bureau of Justice Statistics, 2002). The World Report on Violence and Health (World Health Organization, 2002) tallies the staggering burden of mortality, disease, disability, and compromised well-being brought about by perpetrators of family violence and other violent crimes. Behavioral science needs to achieve a more complete understanding of the causes of antisocial behavior to provide an evidence base for effectively controlling and preventing it. A new wave of intervention research in the last decade has demonstrated clear success for a number of programs designed to prevent antisocial behavior (http://www.preventingcrime.org/; Heinrich, Brown, & Aber, 1999; Sherman et al., 1999; Weissberg, Kumpfer, & Seligman, 2003). Nevertheless, the reduction in antisocial behavior brought about by even the best prevention programs is, on average, modest (Olds et al., 1998; Wasserman & Miller, 1998; Heinrich, Brown, & Aber, 1999; Wilson, Gottfredson, & Najaka, 2001; Dodge, 2003; Wandersman & Florin, 2003). The best-designed intervention programs reduce serious juvenile offenders' recidivism by only about 12 percent (Lipsey & Wilson, 1998). This modest success of interventions that were theory-driven, well-designed, and amply funded sends a clear message that we do not yet understand the causes of antisocial behavior well enough to prevent it.