This chapter discusses policy implications that flow from comprehensive deterrence theory (CDT). The account points to many implications. Perhaps foremost is the conclusion that there simply is insufficient research to ground deterrence-based policies. There are, though, other equally important implications. The chapter argues that, based on CDT, many deterrence-based policies are likely to be ineffective and may increase rather than decrease crime. At the same time, it is likely that deterrence-based policies can be effective, but only under certain conditions. We extend this reasoning to argue that CDT can be used to inform deterrence-based policies in jails and prisons as well as schools.