When inquiring into alternatives to imprisonment, specific attention should be paid to the issue of substance misuse. The reasons for this is the known prevalence of alcohol and drug misuse among offenders in the United Kingdom; the fact that the criminal justice system is one of the primary routes of entry into treatment for substance misuse problems; and the idea that the complexity of the social and environmental contexts of offenders facilitates involvement in crime and drug use. This chapter attempts to draw out theoretical issues and policy implications which are of continuing importance in planning community-based interventions for substance misuse and to examine them within the framework of contemporary policy and practice. It examines the relationship between substance misuse and crime; how individual trajectories of initiation, continuation and desistance from alcohol or drug use develop; theories of substance misuse and addiction; and substance misuse treatment effectiveness. Information in this chapter identifies certain crucial issues that need to be considered when developing treatment provisions for substance-misusing offenders. These issues are presented and discussed. References