Bringing together a large number of criminals -- many of them violent, some with undiagnosed or untreated mental illnesses -- and locking them in a confined space with limited opportunity for rehabilitation or for the release of stress creates a unique social system fraught with danger. To function in such a culture requires knowledge of, and adherence to, very specific rules and structures. In prison, unlike most environments, the stakes of adaption are high. Non-conformity does not simply lead to ostracism; it can lead to victimization or death.
In many ways prisons turn our understanding of deviance on its head. In a world of persons whom society considers deviants, those who do not conform to the (deviant) rules of prison society are the deviants. In some ways, these deviants are more like the normal members of general society than the normal members of criminal society. This is not always true, of course, but in some cases does apply.
It is not unusual, therefore, for individuals in such a situation to band together for safety and survival. However, some groups form more cohesive, complex organizations with their own set of rules that result in activities which move far beyond the simple need to survive in a hostile environment. These gangs often take advantage of their strength within the prison walls to create profit-making enterprises and to disrupt normal prison operations (Camp and Camp, 1985). Prison gangs present a threat not only inside the penitentiary but outside as well, because of their well-established connections with drug trafficking organizations and street gangs. What happens within the razor wire has an impact on society in general not only because most prisoners will eventually be released, but because resources that might have been spent on rehabilitation are spent on combating gang activities (Fleisher and Decker, 2001).
Prison gangs present the sociologist with an opportunity to study a unique social group within a controlled environment and are a good means to compare and contrast the leading theories of social interaction: structural functionalism, symbolic interaction, and conflict theory. Each theory explains a part of why gangs function like they do, however, no single theory can fully explain the rise and continuity of gangs in prison.
To properly study these unique social groups, it is necessary to first define and describe the structure and culture of the gang.
A prison "gang" is more than a loose group of inmates who band together for a common interest. For the purposes of this paper, a prison gang is defined as an ongoing criminal enterprise consisting of multiple actors within a prison, working together for specific goals who use or are willing to use force to promote and protect the enterprise.
In terms of deviance, however, prison gangs represent a unique society because they are comprised of members whom the general society -- the society outside the prison walls -- has defined as "deviant" based on their anti-social behavior. Simply put, members of a prison gang are deviants because they are criminals. However, in the society that prompted their formation -- the prison system -- they are socially accepted and in many cases are the dominant social group.
Prison gangs are therefore representative of the fact that deviance is relative to the time, place and status of the individual or social group. The behavior of a criminal is on its face deviant in general society as is membership in a violent organization whose members are culturally marginalized. In the unique world of prison, however, criminals are not inherently deviant, nor are the groups they join for protection and a sense of belonging.
Culturally, gangs are primarily aligned along race and ethnicity, and operate similarly to their outside counterparts in that they have a relatively flat hierarchy of authority (Kenney and Finkenauer, 1995). Prison gangs are secretive and invariably have a non-revocable initiation process, described as "blood in-blood out" -- a violent act is required of the initiate to join and any attempt to leave the group will result in a violent act against the gangster (Marquart, Kawucha, Trulson, 2006). These rigid rules follow Emile Durkheim's structural functionalism theory which seeks to explain how societies continue to thrive over time because of the various parts functioning together as a cohesive unit.
The rigid rules and strict discipline inherent in a prison gang allow for some sense of stability inside a chaotic environment. Prison gangs, specifically the Mexican Mafia and the Aryan Brotherhood, frequently have written codes of conduct that ensure uniformity across institutions, further bolstering Durkheim's theory of why groups act cohesively over time and space. These groups have their own definitions of deviant who are not allowed to join. The Mexican Mafia, for example, bars homosexuals from membership.
Social control and rational choice might not, at first, appear to explain the prevalence of gangs inside prison walls. However, when prisons are viewed as a functioning society where the generally accepted definitions of deviant and deviancy do not apply, it is obvious that rational choice and social control can explain why convicts join gangs. As noted above, gangs provide safety and power for their members. In a chaotic environment they provide gangsters with a sense of order. Clearly as motivating factors for joining this represent a rational choice. The violent atmosphere inside prison almost requires membership to succeed in that society. Social control inside prison demands that individuals control their behavior based on social standards.
The influence prison gangs have over their environment exemplifies the Marxist conflict theory, which seeks to explain how competing groups attempt to resolve discord within a society. While prison gangs are not divided along class lines, there are sharp divisions by race. The racial groups compete with each other for dominance over things like drug sales or protection rackets. Although a prison gang may not control 100 percent of the drug trade within the prison walls, there is ample evidence that trafficking rarely takes place without the approval or protection of a gang (Fleisher and Decker, 2001).
"Labeling" is also present in prison society, with certain prisoners (e.g. child molesters and sex criminals) considered deviant even in the unique prison environment where the labels given out in general society are almost meaningless. Interestingly, criminals who commit sex crimes within prison (i.e., prisoner rape) are not considered deviant because even in prison rape is a crime of violence, not a sexual act. The more violent a con is, the more status he has in prison society.
In prison how a victim reacts to the violence perpetrated against him to a great extent determines the label he will carry. A convict who retaliates with violence for a victimization can shed the label of a target. A convict who allows his victimization to go unpunished is labeled as deviant, and deviants in prison remain targets of violence.
These rules of society are a reaction to the anomie within prison. Outside the gangs there are no shared, achievable goals. While this would result in increased deviance in general society, in prison the opposite appears to happen. There is still deviance, but there is a rise in non-deviant behavior by prison standards. Prison gangs are not deviant, so those who join them have the opportunity to shed the deviant label. These definitions of deviance have no bearing outside of prison.
Applying the symbolic interactionism theory, where different groups respond to what they perceive the meaning of another group's action rather than simply to the act itself, to prison gang culture is not difficult. For prison gangs, almost anything can have symbolic meaning. For example, tattooing and hand signs are essential components of gang recognition (Fleisher and Decker, 2001). In prison, merely making a gesture that outside prison walls means nothing may provoke a violent response. A bump in the food line is not simply interpreted as a bump, but could be an affront to one's gang or social standing.
None of the major sociological theories can be disproved by studying prison gangs. In fact, the study of prison gangs bolsters the arguments of each of the theories' proponents. The continuity seen in gangs can be explained by structural functionalism, their violent reaction to others is a clear example of class conflict, and the symbols used in communicating gang membership fits soundly within the symbolic interactionism theory.
Understanding the sociology of prison gangs is essential to controlling them and limiting the influence they have both inside and outside of prison. Applying the various theories of social interaction to empirical data may provide some of the answers the criminal justice system seeks.

Bibliography
Camp, M., and Camp, C., (1985) Prison Gangs: Their extent, nature, and impact on prisons. Washington, D.C.: U.S. Department of Justice, Office of Legal Policy.
Fleisher, M. and S. Decker. (2001) An overview of the challenge of prison gangs. Corrections Management Quarterly, 5(1): 1-9.
Kenney, D. J., and Finckenauer, J.O. (1995) Organized Crime in America. Belmont, CA.: Wadsworth Publishing.
Marquart, J.; Kawucha, S.; Trulson, C. (April 2006) "Gang Suppression & Institutional Control" Corrections Today 2 (68): 26.