Some commentators have suggested that there are important differences between American and European gangs, such as the availability of guns, cars, and drugs (Curry and Decker 2003). Researchers contend that this would arguably change the very nature of European gangs compared to American gangs. Curry and Decker (2003) also point out that American and European gangs differ in the type of responses they incur from society. European responses, for example, are more concerned with social opportunity approaches, whereas American responses are more concerned with gang suppression. This chapter will examine the early criminal network and gang development research in Sweden and delineate some of the police responses to the phenomenon. Furthermore, this chapter will address recent gang developments in Sweden and highlight the essential components and working mechanisms of the Stockholm Gang Intervention and Prevention Project (SGIP)—a holistic enforcement response to the growing gang problem in Sweden. SGIP will test various theoretical components of gang enforcement, intervention, and prevention and apply them to street gangs in Stockholm. The goal is to fi nd a method that is practical and applicable to this complex problem. Consequently, this chapter will discuss issues and challenges surrounding the implementation of prevention and intervention policies.