In this chapter the authors first define "crime" and attempt to determine the potential causes of the abrupt change in crime rates over time, as well as the cause of the wide variance in crime among cities. They introduce the economic theory of crime and compare that to theories from other disciplines. The two major categories of reported crimes are: violent crime and property crime. The authors look at the effects of deterrence and see what types of policies work to reduce which types of crime. They review the literature on substance abuse in light of the rational theory of addiction. A hierarchical method of counting crimes consists of only accounting for the most serious act for each incident. The strain theory argues that the failure and frustration of unsuccessful individuals causes them to turn to crime. Originating from psychoanalytic theory, the psychological explanations of crime blame nurture for distorting a criminal's thinking process.