Journal of Aggression, Conflict and Peace Research • Volume 3 Issue 1 • January 2011 © Pier Professional Ltd 12 Introduction The presence of gangs in incarcerated facilities presents a host of issues for policymakers and correctional staff, managers and administrators. Estimates from the US indicate that gang members comprise as much as 13% of jail populations (Ruddell et al, 2006), 12% to 17% of state prison populations (Griffin & Hepburn, 2006; Kreinert and Fleisher, 2001), and nine per cent of the federal prison population (Gaes et al, 2002). These figures take on added significance when considering the violence associated with gangs, inside and outside of prison walls. In large US cities, for example, Decker and Pyrooz (2010) reported that gang members have homicide rates 100 times higher than the national average. Gang members are disproportionately represented in prisons, but our knowledge of prison gangs does not match their level of prison involvement. We attribute this discrepancy to two main sources. First, there are administrative challenges to gathering such information. Correctional agencies screen research proposals and may consider appropriate only those projects with relevance to programmes and operations of correctional institutions. Researchers must also receive approval from university and correctional agencies’ human subjects committee. Second, there are methodological limitations. There are no field studies on prison gangs, and information about prison gang activity must be From the street to the prison, from the prison to the street: understanding and responding to prison gangs David C Pyrooz Doctoral Student, School of Criminology and Criminal Justice, Arizona State University, USA Scott H Decker Foundation Professor, School of Criminology and Criminal Justice, Arizona State University, USA Mark Fleisher Kent State University, USA Invited paper ABSTRACT This article examines a range of issues associated with gangs in incarcerated settings. We begin by examining the similarities and differences between street and prison gangs, and differentiating them from other types of criminal groups. Next, we focus on the emergence and growth of gangs in prison, including patterns and theoretical explanations. Importantly, we draw theoretical linkages between differing perspectives on gang emergence and gang violence. We also present administrative and official responses to gangs in prison. Finally, we discuss the movement from prison to the street, examining the difficulties that former prisoners face when re-entering communities. KEY WORDS Gangs; prison; programming; re-entry. 10.5042/jacpr.2011.0018