This chapter revisits the book’s central argument and conclusions from each chapter. It concludes that there has been substantial misunderstanding about core aspects of deterrence, which can be addressed by working from a comprehensive approach to theorizing deterrence and using this approach to guide and evaluate research. The chapter also concludes that most extant deterrence-based policies cannot and will not appreciably deter crime, and may even worsen it. The solution lies in policies grounded in stronger science built on better theory and research. Our sincere hope is that comprehensive deterrence theory (CDT) provides a helpful step in that direction.