Currently, the criminal justice system does not base its policy-making and decisionmaking on research that has determined what policies are the most effective and the least costly in reducing the most serious crimes that cause the most harm to victims. Although criminology is still in the process of developing a conclusive general theory about the most cost-effective ways to reduce crime, the evidence suggests that mass imprisonment is the most costly and the least effective means for reducing crime. The evidence indicates that the highest percentage of serious crimes that cause the most harm to victims are committed by a relatively small percentage of habitual offenders who commit serious crimes. This in turn suggests that policies of policing and incarceration should focus on the identification, arrest, and incarceration of these high-risk serious offenders. Criminal justice policies and decisions should focus on greater investments in policing, the development of risk assessment instruments, and the management of high-risk offenders, while spending less money on the management of low-risk offenders in the community, and less money on imprisonment (reserved for only serious, violent offenders).