Although research has consistently found that gang members are more involved in serious and violent delinquent offenses than nonmembers, the effect of belonging to a gang has not been separated from the effect of simply associating with delinquent peers. Longitudinal data from both the SSDP and the RYDS provide strong and consistent evidence that being a member of a gang increases the rate of involvement in a variety of deviant behaviors over and above the impact of having delinquent peers. Indeed, gang membership significantly predicts delinquency, even when controlling for other predictors of both delinquency and gang membership.
The consistency and strength of the results of each study are convincing evidence concerning the impact of gang membership on deviant behavior. Even more impressive, however, is the consistency of the results across the two studies. The SSDP and the RYDS have been conducted in cities that differ in their histories and demographic characteristics. For example, the majority of RYDS respondents were African-American (68 percent), while most SSDP respondents were European-American (46 percent). The studies also used somewhat different measures and included somewhat different variables in the multivariate equations. Yet both studies came to the same fundamental conclusion. The fact that both studies generated results that led to the same interpretation reinforces the conclusion that the observed effect of gang membership on involvement in delinquency is not unique to one city or to one ethnic group.