What is a gang? What is the difference between a gang and a peer group? How do you define a gang member? These are three very common and difficult questions to answer across all disciplines. The most common discipline for addressing gangs, their members, and their activities is criminal justice which includes local, state, and federal law enforcement. The problem arises when these three jurisdictions and many others try to agree on a gang definition, which has proven to be a difficult task. In order to reach general agreement on the classification of a group as a gang and an individual as a gang member, avoiding as many discrepancies as possible, James C. Howell presented a chapter, Defining Gangs and Gang Members, in his book, Gangs in America's Communities, which provides a review of early gang definitions, common mannerisms, important factors in gang definition, insights into gang members and gang structure members, and finally discussion of a reasonable and more efficient definition.Summary It is important to first discuss the early definitions derived in response to the early formation of gangs in large cities such as Chicago and Los Angeles due to the large amount of immigration. These definitions provided the basis for further development and recognition for jurisdictions to reach general agreement on how to define a gang and a gang member. The first definitions were rather vague and defined the bare minimum of what a gang might look like and what activities they participated in that researchers discovered in their preliminary research and studies. The first researcher to propose a definition of a gang was Puffer (1912), and he contributed to the gang activity at the center of the article. Youth and Society, 34, 31-54.Howell, J. C. (2012). Definition of gangs and gang members. Gangs in American communities. Klein, M. W. (1971). Street gangs and street workers. Englewood Cliffs, NJ: Prentice Hall.Puffer, J. A. (1912). The boy and his gang. Boston: Houghton Mifflin. Spergel, I. A. (1990). Youth gangs: Continuity and change. In M. Tonry & N. Morris (Eds.), Crime and justice: A review of the research (Vol. 12, pp 171-275). Chicago: University of Chicago. Thrasher, F. M. 1927/2000. The Gang: A Study of 1,313 Gangs in Chicago. Chicago: New ChicagoSchool Press.Tita, G. E., Riley, K. J., Ridgeway, G., Grammich, C., Abrahamse, A., & Greenwood, P. W. (2003). Reducing gun violence: Results of an intervention in East Los Angeles. SantaMonica, CA: RAND.Weisel, D.L. (2002a). Contemporary gangs: An organizational analysis. New York: LFB Academic Publishing.