since the earliest days of gang research, such as the classic study of 1,313 gangs in Chicago conducted by Thrasher (1927), scholars have noted the disproportionate contribution that gang members make to the level of crime in society. Indeed, the observation that gang members, as compared with other youths, are more extensively involved in delinquency – especially serious and violent delinquency – is perhaps the most robust and consistent observation in criminological research.

This observation has been made across time, geographical and national boundaries, and methods of data collection. Observational studies indicate that gang members are heavily involved in various forms of delinquent activities. This finding has been reported in the early research of Spergel (1964), Miller (1966), and Klein (1971), as well as in more recent observational studies, such as those by Moore (1978), Horowitz (1983), Vigil (1988), Taylor (1990), Decker and Van Winkle (1996), and Hagedorn (1998). Studies that rely on official data to compare gang members and nonmembers have also found a strong association between gang membership and delinquent activity (see Cohen, 1969; Huff, 1996; Klein, Gordon, and Maxson, 1986; Klein and Maxson, 1989). Finally, survey research studies report higher rates of involvement in delinquency for gang members as compared with nonmembers. These surveys include Short and Strodtbeck's (1965) study of Chicago gangs, as well as the work by Tracy (1979), Fagan, Piper, and Moore (1986), Fagan (1989, 1990), Huff (1996), and Esbensen and Winfree (1998).